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PERSONAL  LIBRARY 
VERNON  D.  TATE 


ORGANIC  PHOTOGRAPHIC  DEVELOPERS 


COPYRIOKT,  1950.  BY 

FORTY -SECOND  STREET  COM  M srcIAL  STUDIO. 


ORGANIC  PHOTOGRAPHIC 
DEVELOPERS 


By 

Samuel  Wein 


Formerly 

Editor  Perfumery  Art;  Managing  Editor  Color  Trade  Journal 
Author  of  “Modern  Photographic  Developers” 
“Selenium  Cells  and  Hbw'They  are  Made” 


Forty  Second  Street  Commercial  Studio 


1 19  West  42nd  Street 


New  York 


SAMUEL  WEIN 


•r.  • 


PREFACE 


The  major  portion  of  the  literature  of  photographic  developers  is 
of  recent  date.  It  is  true  that  scientific  journals  of  the  latter  part  of 
the  19th  century  are  replete  with  learned  dissertations  on  the  properties 
and  various  compounds  used  as  developers,  but  it  is  quite  natural  that 
it  should  be  so.  The  information  contained  in  such  discussions  is  how- 
ever of  pure  academic  interest. 

Chemists  and  photographers  have  neither  the  time  nor  the  inclina- 
tion to  wade  through  the  “misty  tombs”  in  the  vaults  of  the  libraries. 
In  many  cases  the  original  manuscript  or  patent  have  appeared  in  a 
foreign  tongue,  often  in  a highly  involved  style  and  necessitating  laborous 
dictionary  work  before  a usable  abstract  of  the  required  fact  is  available. 
In  addition  to  this,  many  of  the  libraries  are  closed  to  the  public  during 
the  very  hours  which  the  chemist  or  photographer  usually  has  at  his 
disposal. 

The  following  pages  therefore  constitutes  an  attempt  to  present 
to  the  busy  chemist  and  photographer  a concise  chronological  review  of 
the  literature  of  photographic  developers.  The  aim  in  compiling  the 
work  has  been  to  present  practical  information  alone- — -cold  facts — not 
academic  controversies. 

With  this  explanatory  introduction  the  following  pages  will;  it  is 
hoped,  be  clear  to  all  whose  interest  in  photographic  developers  leads 
them  to  consult  this — a bibliographical  dictionary  of  photographic  de- 
velopers. 

In  conclusion  the  writer  wishes  to  thank  all  those  who  have  helped 
to  make  this  compilation  a possibility,  and  in  particular  to  Mr.  Harvey 
Sears  for  his  assistance  in  typing  and  reading  the  manuscript. 


Samuel  Wein. 


Dedicated 
To  My 
Beloved  Wife 
and  Daughter 
Blanche 


THEGr  . 


CONTENTS 


CHAPTER  I. 


PAGE 


Organic  Photographic  Developers 

CHAPTER  II. 


Dye  Sensitizers 


CHAPTER  III. 

Characteristics  of  Developers 

List  of  Developers  - _ - - 


1-31 


32-35 


36-47 

48-49 


Index 


50-51 


CHAPTER  I. 


Andresen.  German  patent  46915  Aug.  1,  1888. 
Para-phenylenediamine  and  caustic  alkalies  is  employed,  the 
developing  is  rapid  and  even. 

Schwartz  and  Merck! in.  British  patent  741  Jan.  15,  1889. 

Formaldehyde,  para- formaldehyde,  or  hydroxylamine  oxymethy! 
sulphonate  is  added  to  ferrous  oxalate  as  a developing  agent. 


Andresen.  British  patent  5207  March  26,  1889. 


Diamidonapthaline  monosulphonic  acid 
*Diamidonapthaline  disulphonic  acid 
Amidonapthol  monosulphonic  acid 
Amidonapthol  disulphonic  acid 
Dioxynapthaline  monosulphonic  acid 
Dioxynathaline  disulphonic  acid 


C^oH5(NH2)2S020H 
C^OHKNH2)2(S020H)2 
CioH^OH  NH2SQ20H 
CioH^OH  NH2(S020H)2 
Ci0HHOH2)2SO2OH 
Ci0HHOH)2(SO2OH)2 


Stebbings.  Jour.  Soc.  Chem.  Ind.  page  817,  1889. 


Amido  - B - naphthol  - a - sulphonic  acid  and  its  isomeride,  amido 
~ B - napthol  - B - sulphonic  acid  acts  as  energetic  developers.  The 
latter  compound  is  obtained  by  reducing  the  orange  dyestufl:  produced 
by  combining  diazobenzene  chloride  with  Schaeffer’s  B - napthol  • B - 
sulphonic  acid. 

Dimethyl  para-phenylenediamine  may  be  obtained  by  reducing 
nitroso  dimethyl  <miline  with  zinc  dust. 


'^Diamidonaphthol  (obtained  by  reducing  (Martins  yellow)  was  found 
totally  unfit  for  practical  use  on  account  of  its  great  imstability  and 
its  tendancy  to  produce  fogged  images  (Author). 


Meldola.  Jour.  Soc.  Chem.  Ind.  page  958,  1889. 

Heat  1 part  B - napthol  with  twice  its  weight  of  strong  sulphuric 
acid  to  the  temperature  of  boiling  water  till  the  napthalene  is  completely 
sulphonated.  (The  compound  thus  formed  is  commercially  known  as 
“Schaeffer’s  acid”).  This  is  isolated  in  the  form  of  its  ammonium 
salt,  which  gives  the  nitroso  acid  under  consideration.  In  order  to  pre- 
pare the  latter  it  is  only  necessary  to  dissolve  a given  weight  of  ammonium 
or  other  salt  of  Schaeffer’s  acid  in  cold  water  together  with  the  neces- 
sary quantity  of  sodium  nitrite,  and  then,  keeping  the  solution  well 
cooled,  gradually  adding  hydrochloric  acid  to  acid  reaction.  The 
nitrosulphonic  acid  is  at  once  formed  cind  remains  in  the  solution,  impart- 
ing to  the  latter  an  orange  color.  The  acid  can,  if  necessary,  be  isolated 
in  a state  of  purity  in  the  form  of  a barium  or  calcium  salt  (Jour.  Chem. 
Soc.  Trans,  page  44,  1881.). 

By  the  reduction  of  the  nitrosulphonic  acid  an  amido-sulphonic 
acid  is  prepared,  which  is  isolated  (Chem.  Soc.  Trems.  page  47,  1881). 
This  acid  was  the  first  amido-sulphonic  acid  of  naphthol  ever  obtamed, 
and  it  is  the  sodium  salt  of  this  acid  which  is  commercially  known  as 
“Eikonogen.” 

Eikenogen  may  thus  be  made  either  by  the  reduction  of  the  nitro- 
sulphonic acid  or  of  an  azo  derivitive  of  Schaffer’s  acid.  By  the  action 
of  diazobenzene  chloride  upon  this  last  named  acid  an  orange  dye  is 
obtained,  which  is  met  with  in  the  market  imder  the  name  of  “Crocein 
Orange,”  “Brilliant  Orange,”  “Ponceau  4GB,”  etc.  This  may  be 
used  as  a source  of  Eikonogen,  using  stannous  chloride  as  a reducmg 
agent. 

It  would  seem  more  economical,  however,  for  manufacturing  pur- 
poses to  revert  to  the  original  method  and  reduce  the  nitroso  - B - napthol 
sulphonic  acid,  which  need  not  even  be  isolated  for  this  purpose,  but  can 
be  formed  by  the  action  of  nitrous  acid  in  the  manner  previously  de- 
scribed and  reduced  in  the  same  solution.  In  this  process  tin  can  be 
replaced  by  a cheaper  reducing  agent,  such  as  zinc  dust. 

Perkfn.  Chem.  Soc.  Trans,  vol.  57,  page  687,  1890. 

An  almost  quantitative  yield  of  pyrocatechin  can  be  obtained  from 
guaiacol  by  the  following  means:  A solution  of  guaiacol  in  1.5  times 

its  weight  of  fuming  hydriodic  acid  (sp.  gr.  1.96)  is  gently  heated  for 
about  an  hour  in  an  apparatus  fitted  with  a reflux  condenser  (to  con- 
dense the  eliminated  methyl  iodide),  allowed  to  cool,  mixed  with  a 

2 


fourth  of  its  weight  of  hydriodic  acid  and  heated  as  above  for  one  hour. 
TTie  product,  after  washing  with  water,  is  extracted  with  ether,  the  ether 
removed  by  distillation  and  the  residual  oil  purified  by  rapid  distillation. 

Hauff.*  British  patent  15434  Sept  11,  1891. 

Mono'di  and  tetra  ethyl,  methyl,  phenyl,  oxyphenyl,  proyl,  amyl, 
benzyl,  carbonic,  sulphonic  and  holgen  substituted  products  of: 


Example  /. 
AMIDOPHENOLS 


ortho-amido-meta-cresol 

meta-amido-ortho-cresol 

meta-amido-meta-xylenol 

meta-amido-para-xylenol 

ortho-amido-ortho-xylenol 

ortho-amido-meta-xylenol 

para-amido-pyrocatechin 

para-amido-resorcin 

para-diamido'pyrocatechin 

para-diamido-resorcin 

triamidophenol 

triaraido-meta-cresol 


C6H3  CH3  NH2  OH 
C6H3  CH3  NH2  OH 
C6H2(CH3)2  OH  NH2 
C6H2(CH3)2  OH  NH2 
C6H2(CH3)2  OH  NH2 
C6H2(CH*)2  OH  NH2 
C6H»(OH)2  NH2 
C6H3(OH)2  NH2 
C6H2(OH)2  NH2 
C6H2(OH)2(NH)2 
C6H2  OH  (NH2) 

C^H  CH3  OH  (NH2)3 


Example  II. 

amido-oxycarbonic  acid  and  amides,  meta-amido-salicylic  acid 
C6H3  C<yH  NH2  OH  and  amide 
(para-amido-salicylic  acid) 

ortho-amido-meta-oxy-para-tolulic  acid 
C6H2  CH3  C02H  NH2  OH  and  amide 
(para-amido-meta-cresotic  acid) 

meta-amido-ortho-oxy-meta-tolulic  acid 
C6H2  CH3  C02H  NH2  OH  and  amide 
(para-amido-ortho-cresotic  acid) 

*In  the  specification,  Hauif  gives  directions  for  making  up  a de- 
veloping solution  using  “methyl-para-amido-metacresol  (metol).”  This 
appears  to  he  the  first  place  in  which  the  word  “metol”  was  used,  later 
on  Hauff  registered  this  as  a trademark  (Germany  21540  of  1897 — 
England  170477  of  1895;  222388  of  1899,  and  in  America  57145  of  1906). 

3 


B-amido-a-oxy-naphthoic  acid  ^ 

C‘0  H5  (a)  OH  (B)  (B)  C02  H and  amide 

a-amido-a-oxy-naphthoic  acid 
OO  H5  (a)  OH  (a)  NH2  (B)  C02  H 
and  amide 

a-amido-B-oxy-naphthoic  acid 

OO  H5  (a)  NH2  (B)  C02  H (B)  OH 

and  amide 

These  compounds  have  the  property  of  developing  much  slower 
in  alkaline  solutions  than  any  of  the  amido-phenols  already  described, 
but,  however,  it  gives  snappy  and  extraordinary  intensity  in  the  negatives. 

Example  III. 

Of  the  diamines,  reference  is  had  to  the  sulphonic  acids  of:  para- 
phenylenediamine,  para-toluylenediamine,  para-xylenediamine,  a-B- 
naphthy-lenediamine,  a-a-naphthylenediamine,  a-a-amido-naphthol,  a-B- 
amido  naphtol,  B-B-amido-naphthol. 

Reverdin  and  de  la  Harpe.  Chem.  Zeit.  vol.  16,  page  45,  1891. 

Two  hundred  parts  of  phenol  are  added  to  400  parts  of  sulphuric 
acid  (95  per  cent)  which  has  been  heated  to  1 1 0 deg.  and  after  five 
hours  the  temperature  is  raised  to  1 30  to  1 40  deg.  The  mixture  is 
now  diluted  with  600  parts  of  water,  and  a mixture  of  800  parts  of 
nitric  acid  (53  per  cent)  and  575  parts  of  water  (that  is,  1,375  parts 
of  nitric  acid  of  density  1.197)  added  so  that  the  temperature  does 
not  rise  above  45  to  50  deg.  The  whole  is  left  for  twenty- four  hours 
at  the  ordinary  temperature,  after  which  it  is  warmed  slowly  by  means 
of  a waterjacket  for  three  days,  allowed  to  cool,  and  filtered.  The 
product,  which  forms  a crystalline  cake,  is  almost  pure  dinitrophcnol. 
It  is  purified  by  boiling  it  twice  with  2,000  parts  of  water.  The  yield 
is  100  parts  of  dinitrophenol. 

Andresen.  Jour.  Soc.  Chem.  Ind.  page  982,  1891. 

Dimethyl-para-amidophenol  is  prepared  by  diazotizing  dimethyl- 
para-phenylenediamine  and  by  boiling  the  diazo  compound  until  the 
evolution  of  nitrogen  has  ceased.  It  is  recrystallized  from  benzene  and 
is  found  in  large  transparent  crystals,  which  melt  at  74  deg.  C. 

Lumiere.  Jahr.  fur  Photo,  und  Reprod.  technlk  page  93,  1892. 

Oxy  quinoline  or  oxy-tolu  quinoline  are  durable  developers, 

4 


Hauff.  British  patent  4498  Mar.  7,  1892. 

Ortho-para-diamidophenol  develops  without  the  use  of  any  alkali 
whatsoever. 

Hauff.  British  patent  14542,  Aug.  11,  1892. 

Ortho-para  diamidophenol,  ortho-par a-diamido-ortho  cresol,  and 
ortho-para  diamidometa-cresol  are  suggested  as  developers  and  used  in 
a similar  way  as  diamidophenol. 

Lamiere  and  Seyewetz.  Moint.  Scient.  page  30,  1892. 

A compound  in  order  to  behave  as  a developer  must  contain  at 
least  two  hydroxyl  or  two  amido  groups,  or  one  hydroxyl  and  one  amido 
group  joined  to  the  benzene  ring,  these  groups  must  be  either  in  the  ortho 
or  para  positions  to  be  a developer.  The  ortho  compounds  are  the 
weaker  whilst  the  para  compounds  the  more  energetic.  The  meta  corn- 
compounds  do  not  develop  at  all. 

If  one  of  the  hydrogen  atoms  of  a hydroxyl  group  be  replaced  by 
an  alkyl  radicle,  that  is,  an  alcohol  radicle  such  as  ethyl  (C^H^)  or 
by  another  radicle,  then  the  developing  power  is  destroyed,  as  for 
instance  in  phenetroin. 

If,  on  the  other  hand,  one  of  the  hydrogen  atoms  of  an  amido 
group  be  replaced  by  an  alkyl  radicle,  then  the  developing  power  is 
increased,  as  in  the  case  of  para-amidophenol  and  mono-methyl-para- 
amidophenol. 

Besides  the  hydroxyl  and  amido  groups,  the  hydrogen  atoms  of 
the  benzene  ring  may  be  replaced  by  other  radicles,  such  as  carboxyl 
(COOH)  and  the  sulpho  (SO^H)  group,  but  these  reduce  the  develop- 
ing power,  and  in  this  case  the  position  of  the  added  or  substituted 
radicle  plays  an  important  part,  as  in  the  case  of  para-amidophenol- 
meta  carbonic  acid  and  para-amidophenol  ortho  carbonic  acid,  the 
former  being  but  a very  weak  developer,  whilst  the  latter  a vigorous 
developer. 

If  a hydrogen  atom  be  replaced  by  one  of  the  haloid  atoms  of 
bromine,  chlorine  or  iodine,  then  the  developing  power  is  increased,  as 
in  the  case  of  monochlor  (bromine  or  iodine)  hydroquinone. 

If  three  hydrogen  atoms  in  the  benzene  ring  are  replaced  by  three 
amido  or  hydroxyl  groups,  then  the  developing  power  is  increased,  and 
here,  as  in  the  case  of  the  disubstitution  products,  the  ortho,  meta  or 
para  positions  plays  an  important  part,  in  which  pyrocatchine  is  weaker 
than  pyrogallol,  because  in  the  former  there  are  only  two  hydroxyl 

5 


groups  in  the  ortho  position,  whilst  in  the  latter  there  are  three  hydroxyl 
groups  all  in  the  ortho  position.  Again,  if  one  hydroxyl  and  one  amido 
group  be  added  to  the  ring,  then  we  have  a still  more  energetic  developer, 
as  in  the  case  of  para-amidophenol,  whilst  the  addition  of  another  amido 
group  increases  the  action  still  further,  as  in  the  case  of  diamidophenol, 
which  is  at  once  an  ortho  and  a para-amidophenol,  and  diamidoresorcine 
a double  para-amidophenol,  in  which  the  hydroxyl  and  the  amido  groups 
are  in  two  para-positions,  this  is  still  more  energetic. 

Cazeneuve.  Bull.  Soc.  Chim.  vol.  7,  page  549,  1892. 

When  gallic  acid  is  heated  with  twice  its  weight  of  aniline,  car- 
bonic anhydride  begins  to  be  evolved  at  about  1 20  deg. ; and  the  whole 
of  the  gallic  acid  can  be  decomposed  without  raising  the  temperature 
much  above  this  point.  If  the  heating  be  continued  until  the  evolution 
of  gas  is  at  an  end  crystals  of  aniline  pyrogallate  C®H®0®,  2C®H°NH^ 
are  obtained  on  cooling:  this  compound  is  very  unstable  and  melts  at 
55  to  56  deg. ; when  treated  with  benzene  or  toluene  it  is  decomposed, 
aniline  passes  into  solution  and  pyrogallol  remains  in  a practically  pure 
condition. 

Noyes  and  Clement.  Tech  .Quart,  vol.  6,  page  62,  1893. 

When  nitrobenzene  is  dissolved  in  four  times  its  weight  of  sulphuric 
acid  (sp.  gr.  1 .84)  and  electrolysed,  about  40  per  cent  of  the  theore- 
tical yield  of  para-amidophenol  sulphonic  acid  was  obtained  at  50  to 
60  deg.,  whilst  above  1 OO  deg.  charring  occurred.  With  weaker  acid 
(4  grams  water  added  to  1 50  of  sulphuric  acid)  only  para-amidophenol 
sulphate  was  formed,  and  not  its  sulphonic  acid. 

Noyea  and  Gaylord.  Tech.  Quart,  vol.  6,  page  60,  April  1893. 

Para-Amidophenol  sulphonic  acid  acts,  as  a developer,  but  much 
less  energetically  than  para-amidophenol,  a longer  time  is  required,  and 
much  weaker  negatives  are  finally  obtained,  when  negatives  are  developed 
comparatively  with  developing  solutions  identical,  except  that  in  one 
para-amidophenol  is  present,  and  in  the  other,  the  equivalent  quantity 
of  its  sulphonic  acid.  By  increasing  the  quantity  of  sulphonic  acid  five 
or  six  fold,  fairly  good  negatives  could  still  be  obtained. 

AGFA  Co.  British  patent  11872  June  16,  1893. 

By  introducing  amido  or  hyroxyl  groups  into  para-phenylenedia- 
mine  its  developing  charactristics  are  enhanced  to  such  a degree,  that 
the  products  obtained  may  be  used  with  satisfactory  results  in  the 
presence  of  the  ordinary  alkalies. 

Thus  satisfactory  results  can  be  obtained,  by  employing,  for 
instance,  the  following  compounds  as  developers: 


6 


Atnido-paraphenylendmine  (Beilstein  2 edit.  vol.  3,  page  1088). 

Oxy-para  phenylendiamine  (obtained  by  reducing  the  para-dini- 
trophenol  mentioned  in  Beilstein  2 edit.  vol.  2,  page  445). 

Amido-para  toluylenediamine  (obtained  by  the  reduction  of  such 
coloring  matters  as  are  derived  from  a diazo  compound  and  toluylene- 
diamine. 

Baum.  Britlsli  patent  12942  July  1,  1893. 

Into  an  autoclave  fitted  with  a suitable  stirring  device  is  placed 
16  kilograms  potassium  hydroxide  and  17.3  kiolgrams  ortho-bromo- 
phenol  (or  12.85  kilograms  ortho-chlor-phenol) , this  is  heated  to  about 
250  deg.  C.  W^hen  from  6 to  8 hours  have  elapsed  and  the  pressure 
has  risen  from  3 to  4 atmospheres,  the  operation  is  completed. 

The  molten  product  is  dissolved  in  a small  quantity  of  water  made 
acid  (using  either  hydrochloric  or  sulphuric  for  the  purpose).  The 
solution  is  filtered  and  shaken  with  ether,  evaporating  or  distilling  the 
ether,  pyrocatechin  will  be  deposited. 

Baum.  British  patent  21853  Nov,  15,  1893. 

Example  /. 

Fuse  for  8 to  1 0 hours  10  kilograms  sodium  a - phenol  disul- 
phonate  (Ber.  vol.  12,  page  1260)  with  1 0 to  15  kilograms  of  sodium 
hydroxide  in  an  autoclave  at  a pressure  of  2 to  3 atmospheres  at  a 
temperature  of  280  to  300  deg.  C.,  pyrocatechin-monosulphonic  acid 
in  the  form  of  a perfectly  white  mass  will  be  obtained.  This  product 
is  soluble  in  dilute  sulphuric  acid  with  energetic  development  of  sul- 
phurous acid  and  yields  a colorless  acid  solution.  This  is  neutralized 
with  chalk,  concentrated  to  a syrupy  consistency  and  allowed  to  cool. 
The  sodium  sulphate  formed  is  precipitated  and  removed  by  filtering  or 
centrifugal  action.  The  mother  liquid  forming  a violet  solution  which 
with  ferric  chloride  effects  a beautiful  green  coloration,  contains  the 
pyrocatechin  sulphonic  acid  formed  and  this  solution  may  serve  directly 
for  the  production  of  pyrocatechin. 

Example  II. 

Heat  10  kilograms  of  sulphuric  acid  (50  per  cent)  with  the 
pyrocatechin  monosulphonic  acid  formed  in  an  autoclave  from  1 80  to 
220  deg.  C.  The  dark  solution  now  obtained  is  treated  with  steam 
distilliation,  until  the  distillate  with  ferric  chloride  produces  not  a phenol 
reaction  but  a pyrocatechin  reaction,  it  is  then  decolored  with  a little 
anmal  charcoal  and  the  pyrocatechin  agitated  with  ether.  In  this  manner 
more  than  50  per  cent  of  the  theoretical  quantity  of  pyrocatechin  is 
obtained. 


7 


Andresen.  British  patent  25002  Dec.  29,  1893. 

The  following  are  reconunehded  as  developers: 

a-amido-B^  naphthol  monosulphonic  acid,  more  correctly  named 
a^-amido-B*  naphthol  monosulphonic  acid  (Jour.  pr.  Chem.  N.F.B. 
vol.  44,  page  521). 

a-amido-B  naphthol  disulphonic  acid  more  correctly  named 
a^-amido-B^  naphthol  a®  B^  disulphonic  acid,  prepared  by  the  reaction 
of  sulphurous  acid  on  the  nitroso  compound  of  the  B naphthol  mono- 
sulphnic  (Schaeffer’s)  acid. 

The  acid  is  obtained  in  the  shape  of  fine  white  crystalline  needles, 
easily  soluble  in  water,  and  insoluble  in  alcohol.  The  alkali  salts  are 
very  soluble  in  water,  its  solution  turns  brown  after  exposure  for  some 
time  to  the  air. 

a^-amido-B^  naphthol  disulphonic  acid  more  correctly  named 
a*-amido-B^  naphthol-a^  B^  disulphonic  acid,  prepared  by  the  reaction 
of  sulphurous  acid  on  the  nitroso  compound  of  the  B‘-naphthol  B^ 
monosulphonic  acid. 

This  acid  crystallizes  in  the  shape  of  fine  white  needles,  easily 
soluble  in  water  and  insoluble  in  alcohol. 

a*-amido-B'-naphthol-carbo-sulphonic  acid  more  correctly  named 
a^-amido-B*-naphthol-B^  carbo-a®  sulpho  acid,  prepared  by  the  reaction 
of  sulphurous  acid  on  the  nitroso  compound  of  the  B-oxy-naphthoic  acid, 
the  melting  point  of  this  compound  is  2 1 6 deg.  It  is  obtained  in  fine 
crystalline  needles,  sparingly  soluble  in  water  and  insoluble  in  alcohol. 
The  alkali  salts  are  soluble  in  water  and  its  solution  assumes  a brownish 
color  after  exposure  for  some  time  to  the  air. 

Lumiere  and  Seyewetz.  Compt.  Rend.  vol.  116,  page  1202,  1893. 

In  order  to  obtain  para-amidophenol  in  a pure  and  white  form,  its 
hydrochloride  is  dissolved  in  water  and  the  base  liberated  by  using  a 
saturated  solution  of  sodium  sulphite, 

Schering.  German  patent  81068  Apr.  26,  1894. 

Dissolve  1.2  kilograms  phenol  and  2.5  kilograms  sodium  hydr- 
oxide in  75  kilograms  water,  to  this  is  added  3 kilograms  potassium 
persulphate.  This  solution  is  placed  away  for  a day  or  two  and  ex- 


8 


posed  to  tlie  normal  temperature  or  about  40  deg.  Tbe  unacted  on 
phenol  is  distilled  with  steam  and  the  hydroquinone  extracted  with  ether. 

Lumiere  and  Seyewetz.  Bull.  Soc.  Chim.  vol.  11,  page  1038,  1894. 

A mixture  of  30  grams  of  para-nitrotoluene,  200  c.c.  of  water, 
250  c.c.  of  alcohol  and  1 2 grams  of  dry  calcium  chloride  is  heated  to 
boiling.  After  removing  the  flame,  1 50  grams  of  zinc  dust  in  portions 
of  25  grams  are  added  in  the  course  of  half  an  hour.  The  whole  is 
then  boiled  for  about  another  half  hour,  the  liquid  decanted  from  the 
zinc  oxide  and  the  alcohol  distilled  off.  A yellowish  crystalline  mass 
is  obtained,  which,  after  drying  on  a porous  plate  is  washed  with 
petroleum  spirit.  The  resulting  product  para-tolyl-B-hydroxylamine 
CH^  NH  OH  forms  white  plates  melting  at  92  deg.  C.  In  a 

one  per  cent  solution  it  is  gradually  converted  into  para-azoxytoluene 
melting  at  95  deg.  C.  On  boiling  with  mineral  acids  it  is  converted  into 
amldocresol.  Tolyhydroxylamine  and  its  homologes  behaves  as  de- 
velopers. 

Monnet  and  Cartier.  British  patent  24193  Dec.  17,  1895. 

Para-nitrophenol,  unaccompanied  by  the  ortho  compound,  can  be 
obtained  as  follows:  One  hundred  kilos  of  phenol  and  42  kilos  of 
sodium  hydroxide  are  dissolved  in  1 000  litres  of  water,  the  solution  is 
heated  by  means  of  a steam-jet,  and  2 1 0 kilos  of  toluene-para-sulphonyl 
chloride  (a  by-product  in  the  manufacture  of  saccharin)  are  added 
gradually,  and  the  heating  is  continued  until  no  odor  of  the  sulphonyl 
chloride  remains.  On  cooling,  the  ester  is  filtered  off,  washed  with 
water,  and  dried.  A mixture  of  1 00  kilos  of  this  ester  and  1 00  kilos 
of  potassium  nitrate  (or  the  corresponding  quantity  of  nitric  acid)  is 
added  gradually  to  1 000  kilos  of  sulphuric  acid,  the  temperature  being 
kept  at  1 5 deg.  When  the  nitration  is  finished  the  product  is  separated 
from  sulphuric  acid  by  filteration  or  centrifuging  and  well  washed  with 
water.  This  is  the  para-nitrophenyl  ester  of  ortho-nitrotoluene-para- 
sulphonic  acid,  which  when  dried  and  crystallised  from  benzene,  melts 
at  11  5 deg.  The  moist  product  is  suspended  in  an  equal  weight  of 
sodium  hydroxide  solution  (36  deg  Be.),  or  100  kilos  of  the  ester  are 
mixed  with  a solution  of  30  kilos  of  sodium  hydroxide  and  heated  to 
1 00  deg.  until  all  is  dissolved.  On  cooling,  sodium  para-nitrophenoxide 
crystallises  out  and  is  filtered  off  from  the  sodium  o-nitrotoluene-para- 
sulphonate  which  remains  in  the  solution.  The  free  acids  are  obtained 
by  treatment  with  a mineral  acid. 


9 


Paul.  Zeit.  fur  Angew.  Chem.  vol.  9,  page  594,  1896. 

Into  an  earthenware  vessel  (300  litres  capacity)  place  180  kilos 
hydrochloric  acid  (20  deg.  Be.)  75  kilos  of  moist  tin  and  25  kilos  of 
para-nitrophenol  is  gradually  stirred  in.  The  temperature  rises  to  1 00- 
106  deg.,  and  when  all  is  in,  200  kilos  of  sulphuric  acid  (66  deg.  Be.) 
is  added  in  a thin  stream,  the  whole  being  well  stirred.  After  three 
days  the  para-amido-phenol  sulphate  will  have  crystallized  out.  It  is 
filtered  on  a wool  filter,  contrifuged,  dissolved  in  200  litres  of  water 
(cold)  and  the  base  liberated  (if  desired)  with  sodium  carbonate;  some 
tin  is  also  precipitated.  One  kilo  of  sodium  sulphite  dissolved  in  water, 
is  added  to  protect  the  base  from  oxidation.  The  base  is  filtered  off 
and  the  cake  dissolved  in  200  to  300  litres  of  boiling  water  with  the 
addition  of  1 0 kilos  of  sodium  sulphite.  On  filtering  and  cooling,  para- 
amidophenol  crystallizes  in  white  needles.  The  mother  liquor  is  used 
to  dissolve  the  crude  sulphate  in  the  next  batch. 

To  prepare  the  pure  sulphate,  the  crystallized  base  is  boiled  with 
4 to  5 parts  of  water  with  the  addition  of  one  kilo  of  sodium  sulphite 
and  sulphuric  acid,  somewhat  diluted,  is  added  until  an  acid  reaction 
to  Congo  paper  is  obtained.  On  cooling  the  filtered  solution,  the 
sulphate  separates  in  colorless  crystals  which  are  filtered,  centrifuged, 
and  dried.  The  yield  is  12.5  kilos.  The  base  remaining  in  the  liquor 
is  precipitated  by  sodium  carbonate  and  put  into  the  next  batch.  The 
tin  is  precipitated  from  the  waste  liquor  containing  it  by  means  of  scrap 
zinc,  and  is  filtered  off  and  used  again. 

Hauff.  British  patent  27931  Dec.  7,  1896. 

Mono-methyl-ortho-amidophenol  in  molecular  combination  with 
hydroquinone  or  pyrocatechin  forms  energetic  developers.  Other  alkyl 
ortho-amido  substitution  products  is  referred  to,  such  as  the  cresols, 
xylenols  and  napthols,  and  also  its  bromine,  chlorine,  iodine  and  car- 
bonic and  sulphonic  acid  derivitives. 

Paul.  Zeit.  fur  Angew.  Chem.  vol.  9,  page  688,  1896. 

Para-amidophenol  is  made  by  nitrating  phenol,  thus  producing 
ortho  and  para-nitrophenol,  separating  these  by  steam  distillation  and 
reduction  of  the  para-nitrophenol. 

Example  I. 

Phenol  is  nitrated  by  means  of  2 parts  of  nitric  acid  (sp-p.  1.38) 
and  4 parts  of  water.  The  phenol  is  first  liqufied  with  a little  water 
and  run  gradually  into  the  mixture  of  the  nitric  acid  with  2 parts  of 
water  which  is  at  about  8 deg.  The  fourth  part  of  water  is  used  in 

10 


the  form  of  broken  ice,  which  is  added  as  required  to  keep  the  tempera- 
ture below  35  deg.  When  all  the  phenol  has  been  added,  the  mixture 
is  allowed  to  settle  for  one  to  two  hours,  the  liquid  on  the  surface  of  the 
oil  is  siphoned  off  and  the  oil  is  washed  several  times  with  water.  Water 
is  added  and  the  ortho-nitrophenol  distilled  over  by  means  of  indirect 
steam.  The  crude  material  must  be  distilled  again  with  steam,  as  it 
contains  some  phenol.  The  yield  is  36-44  per  cent  of  the  phenol 
employed. 

Example  II. 

Grind  3 kilos  ortho-nitrophenol  with  750  c.c.  of  water  and  2 litres 
of  concentrated  ammonia.  The  pasty  mass  of  the  ammonium  salt  thus 
obtained  is  placed  in  a suitable  vessel  with  6 litres  of  water,  and  heated 
to  20  deg.  The  reduction  is  effected  with  hydrogen  sulphide,  which  is 
passed  into  the  mass  while  it  is  slowly  heated  to  40  deg.  When  the 
conversion  of  the  nitro  compound  is  complete,  the  current  of  gas  is 
stopped.  The  solution  is  allowed  to  stand  for  several  days  and  is  then 
filtered.  The  residue,  after  being  made  into  a paste  with  water  and 
filter  pressed,  is  dissolved  in  hot  water  and  the  ortho-amidophenol 
crystallised. 

The  para-nitrophenol  remains  behind  and  is  extracted  several  times 
with  hot  water,  the  solution  filtered,  and  the  para-nitrophenol  crystallises 
out.  The  mother  liquors,  on  evaporation,  furnish  a further  quantity. 

The  para-nitrophenol  can  be  freed  from  the  tarry  matter  by  re- 
peated crystallisation  from  a little  naphtha,  and  also  by  dissolving  800 
grams  of  the  crude  substance  in  8-10  litres  of  water  and  250  grams  of 
chalk  by  means  of  a current  of  steam,  filtering,  and  adding  to  the  filtrate 
200  grams  of  sodium  carbonate  and  5 kilos  of  salt.  On  filtering,  the 
pure  sodium  salt  of  para-nitrophenol  crystallises  out. 

Gatterman.  Organic  Chemistry  page  248,  1896. 

Dissolve  80  grams  of  sodium  nitrate  in  200  grams  of  water  by 
heating;  after  cooling,  the  solution  is  treated,  with  stirring,  with  100 
grams  of  concentrated  sulphuric  acid.  To  the  mixture  cooled  to  25  deg. 
contained  in  the  beaker,  add  drop  by  drop,  from  a separating  funnel, 
with  frequent  stirring,  a mixture  of  50  grams  of  crystallised  phenol  and 
5 grams  of  alcohol,  melted  by  warming.  During  this  addition  the 
temperature  is  kept  between  25-30  deg.  by  immersing  the  beaker  in 
water.  Should  the  phenol  solidify  in  the  separating  funnel,  it  is  again 
melted  by  a short  warming  in  a large  flame.  After  the  reaction  mixture 
has  been  allowed  to  stand  for  two  hours,  with  frequent  stirring,  it  is 
treated  with  double  its  volume  of  water ; the  reaction-product  collects  as. 

11 


a dark  oil  at  the  bottom  of  the  vessel.  The  principal  portion  of  the 
water  solution  is  then  decanted  from  the  oil,  this  is  washed  again  with 
water,  and  after  the  addition  of  a half  litre  of  water,  is  distilled  with 
steam  until  no  more  ortho-nitrophenol  passes  over. 

After  cooling,  the  distillate  is  filtered,  the  ortho-nitrophenol  washed 
with  water,  pressed  out  on  a porous  plate,  and  dried  in  a desiccator. 
Since  it  is  obtained  completely  pure,  it  is  unnecessary  to  subject  it  to 
any  further  process  of  purification-  In  order  to  obtain  the  non-volatile 
para-nitrophenol  remaining  in  the  flask,  the  mixture  is  cooled  by  immer- 
sion in  cold  water,  the  water  solution  is  filtered  from  the  undissolved 
portions,  and  the  filtrate  boiled  for  a quarter-hour  with  20  grams  of 
animal  charcoal,  the  water  evaporating  being  replaced  by  a fresh  quan- 
tity, The  charcoal  is  then  filtered  off  and  the  filtrate  allowed  to  stand 
in  a cool  place  over  night,  upon  which  the  para-nitrophenol  separates 
out  in  long,  colorless  needles.  The  oil  still  present  in  the  distillation  is 
boiled  with  a mixture  of  1 part  by  volume  of  concentrated  hydrochloric 
acid  and  2 parts  by  volume  of  water,  with  the  addition  of  animal  char- 
coal, filtered  after  partial  cooling  and  the  filtrate  allowed  to  stand  over 
night.  There  is  thus  obtained  a second  crystallisation.  If  the  crystals 
which  have  separated  out  are  still  contaminated  by  the  oil,  they  are 
recrystallised  from  dilute  hydrochloric  acid  with  the  use  of  animal  char- 
coal. 


Gatterir.an.  Organic  Chemistry,  page  206,  1896. 

Add  1 0 grams  of  freshly  distilled  aniline  to  1 00  c.c.  of  concen- 
trated hydrochloric  acid  in  a beaker,  with  stirring:  aniline  hydrochloride 
partially  separates  out  in  crystals.  To  the  mixture,  cooled  with  ice, 
add  slowly  from  a dropping- funnel,  a solution  of  10  grams  of  sodium 
nitrite  in  50  c.c.  of  water,  until  a test  with  starch-potassium-iodide  paper 
shows  free  nitrous  acid.  In  this  case  the  strong  acid  solution  must  not 
be  brought  directly  upon  the  test-paper,  but  a test-portion  is  diluted  with 
water  on  a watch-glass  and  then  the  test  applied.  To  the  diazo-solution 
add,  with  stirring,  a solution  of  60  grams  of  stannous  chloride  in  50  c.c. 
of  concentrated  hydrochloric  acid  cooled  with  ice;  a thick  paste  of 
crystals  of  phenyl  hydrazine  hydrochloride  separates  out.  After  stand- 
ing an  hour  this  is  filtered  off  with  suction. 

Paul.  Zeit.  fur  Angew.  Chem.  vol.  9,  page  688,  1896. 

The  tarry  matter  found  in  the  manufacture  of  para-nitrophenol 
may  be  freed  by  repeated  crystallization  from  naptha,  or  by  dissolving 
800  grams  of  the  crude  substance  in  8 to  10  litres  of  water  and  250 
grams  of  chalk  by  means  of  a current  of  steam,  filtering,  and  adding  to 
the  filtrate  2C0  grams  of  sodium  salt  of  para-nitrophenol  crystallizes 
out. 


12 


Lembach  & Schleicher.  British  patent  371,  January  6,  1896. 

Ethyl,  methyl,  propyl,  benzyl,  amyl  and  oxyhydro  derivitives 
of  ortho  and  para  quinoline  are  found  to  act  as  developers.  These  com- 
pounds were  first  described  in  Ber.  vol.  16,  pages  714,  717,  719 
and  756. 

Buisson.  British  patent  10284  May  2,  1896. 

A paste  is  made  of  100  grams  para-amidophenol  (or  diamido- 
phenol) , 1 00  grams  hydroquinone  (or  pyrocatechin)  with  200  grams 
glycerine  (or  alcohol),  this  is  stirred  in  a mortar  and  then  poured  into 
2 litres  of  water.  Add  an  equal  volume  of  sulphite  solution  containing 
25  per  cent  potash,  a bulky,  flaky  white  precipitate  is  deposited,  while 
the  supernatent  liquid  is  colorless  and  later  on  becomes  bluish  violet. 
The  precipitate  is  thrown  on  a filter  and  washed  several  times  with  a 
5 per  cent  solution  of  potassium  meta  bisulphite,  in  order  to  prevent 
oxidation  of  the  precipitate,  it  is  dried  in  a current  of  dry  sulphurous 
acid. 

This  compound  is  dissolved  in  water  and  ready  for  use  on  addi- 
tion of  a little  sodium  carbonate. 

Hauff.  British  patent  11306  May  23,  1896. 

Compounds  made  from  one  molecule  para-phenylenediamine  and 
one  molecule  hydroquinone  (or  pyrocatechin)  forms  a developer  that 
is  more  energetic  and  clearer  in  detail  than  those  made  up  of  two  mole- 
cules of  hydroquinone. 

Molecular  combinations  between  hydroquinone  (or  pyrocatechin) 

with: 

para-toluylenediamine 

para-xylenediamine 

a-a-naphthylenediamine 

o-5-naphthyIenediamine 

and  its  alkyl,  carboxyl,  chlorine,  iodine,  bromine,  oxy  or  amido  sub- 
stituted products  are  suggested  as  developers. 

Schering.  German  Patent  111798  Dec.  30,  1897. 

Halogen  (bromine,  chlorine  and  iodine)  disubstitution  products 
of  hydroquinone,  pyrocatechin  and  pyrogallol  is  referred  to  as  developers. 

Vidal.  British  patent  5697  Mar.  3,  ISO"?. 

Into  an  iron  vessel  fitted  with  an  agitator  is  placed  2 kilos  100 
grams  of  oxyazobenzene,  3 kilos  sodium  sulphide  and  1 kilo  sodium 
hydroxide.  The  mass  is  heated  to  1 80  deg.  C. ; and  sufficient  water 
is  added  until  the  yellow  color  has  disappeared. 

13 


The  mass  is  dried  and  again  dissolved  in  water,  para-amidophenol 
is  precipitated  by  an  acid. 

Ortho-and  di-nitrophenol  is  treated  in  the  same  way  in  order  to 
obtain  the  corresponding  amido  compounds. 

Cassella.  British  patent  26136  Oct.  29,  1897. 

Grind  10  grams  acetyl-oxyazobenzene  (Wallace  and  Kiepenheuer 
Ber.  vol.  14,  page  2617)  and  gradually  introduce  this  into  60  c.c. 
hydrochloric  acid  (38  per  cent),  stirring  the  mass  continuously.  The 
temperature  of  the  solution  is  raised  and  care  has  to  be  taken  that  by 
.cooling  with  cold  water,  the  temperature  does  not  exceed  40  deg.  C. 
After  standing  about  a day,  a large  quantity  of  double  salts  of  tin  con- 
sisting chiefly  of  oxydiamid  di  phenyl  and  of  a small  quantity  of  benz’d- 
ine  separates  from  the  solution.  By  strong  extraction  and  pressing  any 
hydrochloric  acid  adhering  is  as  far  as  possible  removed  from  it.  This 
double  salt  is  then  dissolved  in  about  20  parts  of  water;  the  tin  is  pre- 
cipitated with  hydrogen  sulphide  and  the  solution  from  which  the  tin 
has  been  filtered  off  is  strongly  evaporated  in  a stream  of  carbonic  acid. 
By  adding  dilute  sulphuric  acid  the  benzidine  is  separated  in  the  form 
of  its  difficulty  soluble  sulphate.  After  having  ascertained  that  sul- 
phuric acid  no  longer  causes  a precipitate  from  the  solution  the  benzidine 
sulphate  is  filtered  off,  the  solution  partially  neutralised  with  sodium 
hydroxide  and  then  completely  with  a concentrated  solution  of  sodium 
carbonate.  The  oxydiamido  diphenyl  thereby  is  separated  partly  as  a 
white  crystalline  and  partly  as  a resinous  precipitate.  This  is  then 
purified  by  crystallisation  from  water  or  benzene. 

Its  melting  point  is  1 48  deg.  C. ; and  is  easily  soluble  in  hot  water 
and  readily  soluble  in  alcohol. 

Darmstadter.  German  patent  109012  of  1897. 

Electrolytic  reduction  of  analine  and  chromic  acid  produces  hydro- 
quinone. 

Hauff.  British  patent  28596  Dec.  3,  1897. 

The  addition  of  an  alkyl  group  to  para-phenylenediamine,  para- 
toluylenediamine,  para-xylenediamine,  a - B - naphtylenediamine,  a ~ a - 
naphtylenediamine,  will  give  rise  to  a developer  that  is  both  fast  and 
permanent  in  solution. 

Paul.  Zeit.  fur.  Angew.  Chem.  vol.  10,  page  171,  1897. 

Add  250  grams  para-nitrophenol,  45  grams  hydrochloric  acid 
(30  deg.  Be.)  and  500  c.c.  of  water  in  an  iron  vessel  provided  with 
an  agitator,  this  is  heated  to  98  deg.  C.  and  add  (in  portions  of  1 5 to 
20  grams)  400  grams  of  iron  borings  so  long  as  a vigorous  reaction 

14 


takes  place.  The  whole  is  then  boiled  for  half  an  hour  and  extracted 
with  about  2 litres  of  water  and  25  to  30  grams  sodium  carbonate.  The 
filtered  solution  deposits  para-amidophenol  on  cooling  and  the  mother 
liquor  is  used  for  the  next  extraction,  which  is  continued  as  long  as  para- 
amidophenol  crystallizes  out  on  cooling.  The  yield  is  140  grams  cor- 
responding to  71  per  cent  of  the  theoretical. 

That  metol  cannot  be  made  by  direct  methylation  of  para-amido- 
phenol is  the  result  of  a number  of  experiments.  This,  however,  he 
obtained  by  boiling  for  about  one  hour  in  aqueous  solution,  two  molecules 
of  para-amidophenol  and  one  molecule  of  chloracetic  acid.  On  cooling, 
para-hydroxyglycine  crystallises  out,  which  on  heating  turns  brown  at 
200  deg. ; begins  to  melt  at  220  deg.  and  is  completely  melted  at  245 
to  247  deg.  C.,  when  it  decomposes  in  carbonic  acid  and  metol  base 

The  product  is  then  isolated  in  its  sulphate  form  in  order  to  enable 
it  to  be  used  in  watery  solutions. 

Hauff.  British  patent  13195  June  13,  1898. 

The  halogen  (bromine,  chlorine  and  iodine)  substitution  products 
of  hydroquinone,  hydrotoluquinone,  pyrocatechin,  pyrogallol  and  hydro- 
naphtoquinone  and  B - hydronaphtoquinone  are  suggested  as  developers. 

AGFA  Co.  British  patent  21595  Oct.  13,  1898. 

Diamido-napthol  disulphonic  acid  obtained  by  reducing  the  azo 
dyestuffs  derived  from  acid  H,  acid  K and  acid  S are  suggested  as 
developers. 

Levinstein  and  Poliak.  British  patent  13178  June  26,  1899. 

Suspend  a^amido-a^-nitro-a*  sulphonic  acid  in  water  to  which 
there  is  then  added  an  equivalent  proportion  of  an  alkali.  The  resulting 
solution  is  then  run  into  a reducing  mixture  of  iron  and  acetic  acid,  and 
heated  for  some  hours.  After  the  reaction  is  finished,  the  dissolved 
iron  is  precipitated  with  magnesia,  and  a'^-a^-naphth^lenediamine  (a^) 
sulphonic  acid  is  obtained  from  the  filtrate  by  precipitation  with  hydro- 
chlorc  acid.  It  forms  greyish  needles  and  oxidises  easily  in  alkaline 
solution. 

It  develops  very  slowly  and  is  of  advantage  in  the  development 
of  over  exposed  negatives. 

Cramer.  Photo.  Mittheil.  vol.  36,  page  164,  1899. 

Halogen  substitution  compounds  have  many  advantages  over  the 
aromatic  bodies  containing  simply  hydroxyl  or  amido  groups,  which  have 
hitherto  been  employed  or  investigated  as  photographic  developers.  In 
particular,  the  bromine  derivitives  of  hydroquinone  and  pyrogallol  are 

15 


much  more  energetic  than  the  original  substances;  the  former  gives  softer 
negatives  and  the  latter  is  among  the  most  rapid  developers.  They  are 
prepared  by  mixing  together  calculated  proportions  of  hydroquinone  or 
pyrogallol  with  free  bromine,  both  dissolved  in  benzene;  a second  crys- 
tallization ensuring  purity.  Chlorine  compounds  behave  similarly. 

Lumiere  and  Seyewetz.  Monit.  Scient.  vol.  13,  page  168,  1899. 

Hydroquinone  and  para-phenylene-diamene  unite  in  molecular 
proportions  to  form  brilliant  white  scales. 

Kempf.  German  patent  117251  of  1899. 

The  electrolytic  oxidation  of  benzene  and  sulphurous  acid  produces 
hydroquinone. 

Tauber.  German  patent  82426. 

Para-amidophenol  is  obtained  from  para-azophenol  OH  C®H^ 
N‘C®H^  OH  (prepared  by  combining  diazotised  sulphanilic  acid  with 
phenol  and  fusing  the  product  with  sodium  hydroxide)  by  reduction 
with  stannous  chloride  or  with  zinc  dust  and  sodium  hydroxide. 

Meister  Lucius  and  Bruning.  German  patent  96853. 

This  method  consists  in  dissolving  30  kilos  of  nitrobenzene  in  250 
kilos  of  sulphuric  acid,  adding  50  kilos  of  zinc  dust  at  50  to  80  deg. 
within  four  hours,  and  keeping  the  mixture  for  ten  hours  at  this  tempera- 
ture. It  is  then  cooled  and  poured  on  ice,  when  the  para-amidophenol 
sulphate  crystallizes  out. 

Darmstadter.  German  patent  150800. 

In  manufacturing  para-amidophenol  by  electrolysis  a large  quan- 
tity of  aniline  is  formed.  This  latter  is  detrimental  to  the  yield,  and  is 
avoided  by  using  carbon  cathodes  placed  in  to  a solution  consisting  of 
100  grams  nitrobenzene  in  1 kilo  of  sulphuric  acid  (85  per  cent).  The 
current  density  required  to  obtain  the  best  results  are  4 amperes  per 
square  decimeter. 

Bayer.  German  patent  43515. 

Ortho-nitrophenol  is  obtained  by  nitrating  phenol  para  sulphonic 
acid  and  subsequent  hydrolysis  with  superheated  steam,  but  Paul  (Zeit- 
fur  Angew  Chem.  vol.  9,  page  588,  1896)  was  able  to  obtain  only 
a 25  to  33  per  cent,  yield  of  the  theoretical  by  this  process. 

Darmstadter.  German  patent  154086. 

An  improved  process  for  making  para-amidophenol  by  electrolysis 
is  by  using  1000  c.c.  of  (50  per  cent)  sulphuric  acid  and  250  grams 
of  nitro  benzene  in  the  cathode  space,  and  40  per  cent  in  the  anode 
space,  which  is  diluted  as  it  becomes  concentrated  as  the  result  of  elec- 
trolysis. The  cathodes  are  carbon  and  the  anodes  are  lead  plates. 
With  a current  density  of  6 amperes  per  square  decimeter,  about  200 


16 


ampere  hours  are  required  to  reduce  about  200  grams  of  nitrobenzene. 
After  cooling  the  nitrobenzene  is  separated  and  the  para-amidophenol 
sulphate  is  filtered  off.  The  solution  is  strengthened  by  the  addition 
of  sulphuric  acid  and  used  again. 

Vidal.  French  patent  315696. 

A solution  of  1 92  kilos  of  sulphuric  acid  (95  per  cent.)  is  run 
into  a solution  of  1 72  kilos  of  sodium  nitrate  in  1 700  litres  of  water. 
The  mixture  is  allowed  to  remain  for  several  hours,  and  then  slowly 
heated  until  the  gas  evolution  ceases.  On  cooling,  the  dimitrophenol 
is  filtered  off. 

Bayer.  British  patent  10721  May  23,  1901. 

Example  /. 

A watery  solution  of  1 26  parts  of  pyrogallol  is  added  to  225 
parts  of  a 20  per  cent  solution  of  dimethylamine  and  the  resulting  mixture 
is  then  allowed  to  stand  at  the  ordinary  temperature.  After  some  time 
the  liquid  becomes  hot  spontaneously,  a precipitate  of  large  prisms  being 
separated  in  the  mixture.  When  the  reaction  is  finished,  the  precipitate 
is  filtered  off,  contact  with  the  air  being  avoided,  and  it  is  then  dried  at 
a low  temperature,  is  easy  soluble  in  water,  soluble  with  difficulty  in 
alcohol  and  insoluble  in  ether.  Its  melting  point  is  1 63  deg.  C. 

The  process  proceeds  in  an  analogous  manner,  if  other  aliphatic  or 
cyclic  amines  are  employed.  The  melting  points  of  some  of  these  new 
derivatives  of  pyrogallol  are  given  in  the  following  table: 


Derivative  obtained  from  pyrogallol  with  Melting  point 

trimethylamine  160  deg.  C. 

Monomethylamine  124  deg.  C. 

Piperazine  150  deg.  C. 

Piperidine  177  deg.  C. 

Quinoline  72  deg.  C. 

Oxyquinoline  112  deg.  C. 

Triacetonamine  98  deg.  C. 


Example  II. 

0.2  litres  of  a 22.5  per  cent,  solution  of  dimethylamine  are  poured 
into  a solution  of  0. 1 1 kilos  of  resorcine  in  0.3  litres  of  ether.  Sub- 
sequently petrol  ether  is  added,  until  a solid  body  begins  to  be  separated. 
After  about  24  hours  the  new  compound  has  precipitated  in  the  shape 
of  prisms  melting  at  82  deg.  C. 

The  new  product  obtained  from  resorcin  and  quinoline  melts  at 
75  deg.  C.,  that  from  resorcin  and  oxyquinoline  melts  at  95  deg.  C. 

The  corresponding  derivatives  of  other  phenols  are  produced  in  an 
analogous  manner. 


17 


Hereunder  the  melting  points  of  some  representatives  of  these 


bodies  are  given. 

The  combination  obtained  from: 

dimethylamine  and  pyrocatechin 115  deg.  C. 

monomethylamine  and  pyrocatechin 98  deg.  C. 

dimethylamine  and  hydroquinone 132  deg.  C. 

triacetonamine  and  hydroquinone 108  deg.  C. 


Other  phenol  like  bodies  containing  several  groups  react  in  an 
analogous  manner,  such  as  the  phenol  carboxylic  acids  or  the  like.  The 
compound  obtained  from  dimethylamine  and  the  methylic  ether  of 
gallic  acid  melts  at  164  deg.  C. ; the  dimethylamine  ethylic  ether  of 
this  acid  melts  at  79  deg.  C. ; and  free  from  water  at  about  122  deg. 
C.  The  combination  of  piperdine  with  the  ethylic  ether  of  gallic  acid 
melts  at  1 70  deg.  C. ; and  that  of  dimethylamine  with  the  ethylic  ether 
of  alpha-resorcylic  acid  at  95  deg.  C. ; whilst  the  combination  dimethy- 
lamine-gallacetophenone  has  the  melting  point  156  deg.  C. 

Bayer.  German  patent  157667  April  26,  1901. 

Acetyl-para-amidosaligenin  is  found  to  develop  energetically. 

Bayer.  British  patent  12421  June  18,  1901. 

Example  /. 

Add  5 parts  zinc  chloride  to  a solution  of  1 0 parts  of  paranitro- 
phenol  in  8 parts  of  chloromethylic  alcohol.  The  mixture  turns  hot 
spontaneously.  After  about  24  hours  the  new  compound  precipitated 
in  the  mixture  during  the  reaction  is  filtered  off  and  purified  by  a re- 
crystallization from  benzene. 

It  represents  small  needles  meltmg  at  1 32  deg.  C.  The  new 
compound  is  easily  soluble  in  alcohol,  benzene,  glacial  acetic  acid  and 
chloroform  and  soluble  with  difficulty  in  ligroine  and  ether. 

The  corresponding  compound  containing  iodine,  melts  at  1 69 
deg.  C. 

On  employing  in  the  above  example  ortho-nitrophenol,  a new 
product  is  obtained  which  crystallizes  in  the  shape  of  yellow  needles, 
melting  at  75  deg.  C.  Tire  corresponding  derivative  containing  bromine 
melts  at  76  deg.  C.  and  that  containing  iddme  has  a melting  point  of 
1 1 2 deg.  C. 

Example  II. 

1 0 parts  of  concentrated  sulphuric  acid  are  added  to  a mixture 
prepared  from  1 ,500  parts  of  concentrated  hydrochloric  acid,  300  parts 
of  a 40  per  cent,  solution  formic  aldehyde  and  1 00  parts  ortho- 
chlorophenol.  The  reaction  mass  is  allowed  to  stand  for  about  one 
hour  with  a shaking  from  time  to  time.  The  new  compound  precipitated 
during  the  reaction  is  filtered  off  and  purified  by  a recrystallization  from 
ligroine.  It  melts  at  11 2 deg.  C. 

The  corresponding  derivative  obtained  from  para-chlorophenol 
melts  at  85  deg.  C. 


18 


Example  111. 

200  parts  of  para  nitrophenol  are  introduced  into  a mixture  of 
1 ,800  parts  of  concentrated  hydrochloric  acid,  20  parts  of  sulphuric 
acid  (66  degrees  Be.)  and  300  parts  methyl  0.4  (CH^  (OCH^)  ^). 
It  is  heated  on  the  water  bath  at  from  65  to  70  deg.  C.  for  several 
hours,  conducting  into  the  reaction  mass  a current  of  hydrogen  chloride. 
After  cooling,  the  crystalline  precipitate  is  filtered  off  and  recrystallized 
from  benzene,  the  nitro-oxybenzyl  chloride  thus  obtained  melts  at  1 32 
<deg.  C. 

The  process  proceeds  in  an  analogous  manner  if  in  the  above 
examples  other  nitrated  or  halogenated  phenols  are  used. 

In  order  to  illustrate  the  production  of  the  above  mentioned  deriva- 
tives of  these  bodies  the  following  examples  4 and  5 are  given,  the 
parts  being  by  weight. 

Example  IV, 

100  parts  of  chloromethylic-orthonitro-phenol  are  dissolved  in 
alcohol  and  the  resulting  solution  is  heated  on  the  water  bath  for  about 
4 hours  neutralizing  from  time  to  time  the  hydrochloric  acid  set  free 
during  the  reaction.  After  the  alcohol  of  the  solution  has  been  partially 
evaporated,  the  new  product  separates  in  the  shape  of  an  oil  which 
solidifies  to  crystals,  melting  at  26  deg.  C. 

Example  V. 

A mixture  prepared  from  100  parts  of  chloro-methylic-orthoni- 
trophenol  and  1 ,000  parts  of  water  is  heated  for  some  time.  From  the 
filtered  solution,  the  new  product,  having  most  probably  the  formula : 
precipitates  in  the  shape  of  well  formed  crystals  melting  at  97  deg.  C. 

The  corresponding  derivative  obtained  from  para  nitrophenol  melts 
at  1 28  deg.  C.  That  derived  from  o-chlorophenol  melts  at  i 05  deg. 
C.,  whilst  the  corresponding  derivative  of  para  chlorphenol  has  the 
melting  point  148  deg.  C. 

The  derivatives  of  the  nitrated  or  halogenated  phenols  containing 
the  group  CH^OH  can  also  be  prepared  from  the  said  starting  materials 
in  a single  operation.  For  this  purpose,  it  is  only  necessary  to  heat,  for 
instance,  the  reaction  mixture  of  the  examples  1 and  2 with  water. 

The  following  example  6 may  illustrate  the  above  mentioned 
reduction  of  the  nitrated  bodies,  their  ethers  and  esters,  obtained  by  the 
new  process. 

Example  VI. 

2 parts  of  tin  are  added  to  a mixture  of  1 part  of  nitro-para  oxy- 
benzyl  alcohol  and  10  parts  of  concentrated  hydrochloric  acid.  The 
reaction  goes  on  quietly  and  can  be  accelerated  by  heating.  After  cool- 
ing, the  double  salt  of  tin  of  the  new  amido  para,  oxybenzyl  alcohol 

19 


separates.  It  is  dissolved  in  water  and  decomposed  by  a solution  of 
sodium  carbonate,  the  free  amido  para  oxybenzyl  alcohol  is  dissolved  in 
ether  from  which  solution  it  is  obtained  in  a solid  state. 

The  new  base  thus  obtained,  crystallizes  in  the  shape  of  colorless 
leaves  readily  soluble  in  hot  water  and  in  alcohol  ^nd  ether.  It  melts 
at  from  1 35  to  1 42  deg.  C. 

The  corresponding  amido  compound  obtained  from  nitro  para 
oxybenzylmethylether  having  most  probably  the  fomula: 

OH  NH2  CH^’OCH3 

represents  slightly  yellowish  leaves  melting  at  1 25  to  1 26  deg.  C. 

The  process  proceeds  in  an  analagous  manner  if  other  reducing 
agents  or  other  of  the  above  mentioned  nitro  compounds  are  used. 

Eichengrun  and  Demeler.  United  States  patent  696020  Mar.  25, 

1902. 

Dissolve  1 0 parts  para-nitrophenol  in  8 parts  chlor  methyl  alcohol. 
To  this  solution  add  5 parts  zinc  chloride.  The  mixture  immediately 
turns  hot. 

After  24  hours  the  new  compound. 

Chlor  methyl  para  nitrophenol  (CH^Cl)  OH  NO^ 

is  precipitated  from  the  mixture,  in  the  form  of  fine  crystals  or  needles, 
its  melting  point  being  about  i 32  deg.  C.  These  needles  are  filtered 
from  the  solution  and  are  purified  by  recrystallization  from  methyl 
alcohol. 

Subsequently  a mixture  prepared  from  the  chlor  methylic  para- 
nitrophenol  is  thus  obtained  and  the  ten  fold  quantity  of  water  is  heated 
for  some  time  until  a clear  liquid  or  solution  results.  From  the  filtered 
solution  the  new  product  having  the  formula: 

C<5H3  (CH3  OH)  OH  N02. 

is  precipitated  on  cooling  in  the  shape  of  crystals,  melting  at  about  1 28 
deg.  C.  In  order  to  reduce  the  said  body,  two  parts  of  tin  are  added 
to  a mixture  of  1 part  methyl  para-nitrophenol  and  1 0 parts  of  concen- 
trated hydrochloric  acid.  The  reaction  goes  on  quietly  and  can  be 
accelerated  by  heating.  After  cooling  the  double  salt  of  tin  of  the  new 
methyl  para-amidophenol  separates  out.  It  is  dissolved  in  water  and 
decomposed  by  a solution  of  sodium  carbonate.  The  free  methyl-para- 
amidophenol  is  dissolved  in  ether  and  when  the  ether  is  extracted  from 
this  solution  the  salt  is  obtained  in  a solid  state.  The  new  salt  has  the 
following  formula: 

CCH3  (CH2  OH)  OH  NH\ 

and  appears  in  the  form  of  colorless  needles  or  leaves,  which  are  de- 
composed when  in  contact  with  warm  air,  it  is  soluble  in  hot  water, 
alcohol  and  in  ether,  melting  at  from  1 32  to  1 42  deg.  C.  It  forms 
salts  with  acids  and  alkalies  and  it  is  therefore  advisable  to  form  this 
in  the  form  of  a hydrochloride  or  sulphate,  in  order  to  make  the  finished 
product  more  soluble  in  water  and  at  the  same  time  a stable  compound. 

20 


Lumiere.  French  patent  322402  June  28,  1S02, 

Example  /. 

Benz  amido  semicarbide. 

Take  100  parts  diamidobenzamine,  100  parts  alcohol  and  100 
parts  hydrochloric  acid,  to  this  add  40  parts  of  an  aqueous  sodium 
nitrite  solution.  A precipitate  will  form,  which  is  diazo-amido 
benzamide. 

Example  II. 

Benzamide  hydrazine. 

To  the  diazo-amido  benzamide  add  300  parts  hydrochloric  acid 
and  a mixture  700  parts  stannous  chloride  and  600  parts  hydrochloric 
acid,  a crystalline  precipitate  will  form  consisting  of  a double  salt  of 
hydrazine  benzamide.  Dissolve  the  double  salt  in  750  parts  hot  water 
and  allow  hydrogen  sulphide  to  pass  through,  in  order  that  the  tin  will 
precipitate  out. 

1 he  double  salt  of  tin  and  hydrazine  benzamide  when  decom.- 
pased  by  hydrogen  sulphide,  forms  stannous  sulphide  and  two  molecules 
of  hydrochloric  acid,  to  which  is  added  while  in  solution  a sufficient 
amount  of  sodium  carbonate  to  neutralize  the  hydrochloric  acid.  Hydra- 
zine benzamide  hydrochloride  will  form.  Boil  until  the  hydrogen  sulphide 
is  disposed  of. 

Example  III. 

Benzamide  semicarbazide. 

Make  an  aqueous  solution  of  30  parts  potassium  cyanide  and  pour, 
drop  by  drop  into  the  solution  under  example  1 . The  benzamido  semi- 
carbazide will  instantly  precipitate,  this  is  collected  and  purified  by 
recrystallizing  from  water. 

Meicter,  Lucius  and  Bruning.  British  patent  20377  Sept.  18,  1902. 

The  addition  of  sodium  glycocol  (and  its  methyl  derivitative)  to 
pyrogallol,  hydroquinone,  diamidophenol,  edinol  and  Eikonogen  is 
advocated  as  a rapid  developer. 

Bayer.  British  patent  3545  Feh.  14,  1903. 

Mcita-amido-ortho-oxy  benzyl  sulphonic  acid  is  made  by  reduc- 
ing its  corresponding  nitro  compound  (British  patent  12421,  June  18, 
1901),  as  follows:  10  parts  of  meta-nitro-otho-oxybenzyl  chloride  is 

added  to  a solution  of  1 3.4  parts  of  sodium  sulphite  in  1 00  parts  of 
water  and  the  resulting  mixture  is  allowed  to  stand  for  several  days, 
stirring  it  from  time  to  time.  It  is  filtered  and  acidulated  with  hydro- 
chloric acid  and  the  sodium  salt  of  meta-nitro-ortho  oxybenzyl  sulphonic 
acid  is  precipitated  by  the  addition  of  sodium  chloride.  A solution  of 

21 


1 0 parts  of  the  sodium  salt  thus  produced  in  20  parts  of  water  is  then 
boiled  with  1 5 parts  of  zinc  dust  until  the  liquid  has  become  uncolored. 
It  is  filtered  from  the  filtered  solution  the  sulphonic  acid  is  precipitated 
by  the  addition  of  hydrochloric  acid. 

Lumiere.  British  patent  7163  Mar.  27,  1903. 

To  an  aqueous  (concentrated)  solutions  of  two  molecules  methyl- 
amido  para-azoxybenzene  sulphate  (or  free  base)  to  one  molecule 
hydroquinone  is  added  100  grams  sodium  sulphite  per  litre  of  solution. 
At  the  end  of  a short  period  a precipitate  of  white  nacreous  needles  will 
form,  this  latter  is  readily  separated  from  the  solution. 

The  melting  point  of  this  product  is  1 40  deg. 

Tafel.  United  States  patent  727025  May  5,  1903. 

Example  /, 

An  electrolytic  cell  is  separated  into  an  anode  and  cathode 
chamber  by  a diaphragm.  The  cathode  chamber  is  filled  with  6 kilo- 
grams of  sulphuric  acid  (50  per  cent).  Each  chamber  of  the  cell  is 
provided  with  means  for  cooling.  The  cathode  consists  of  well  amal- 
gamated lead,  while  the  anode  is  formed  of  pure  lead.  A current  of 
60  to  1 20  amperes  per  square  decimeter  is  now  sent  through  the  bath, 
both  spaces  of  the  cell  being  well  cooled.  Thereupon  2 kilograms  of 
nitric  acid  (50  per  cent  solution)  are  added  slowly  to  the  bath  by  a 
dropping  apparatus,  so  that  always  a slight  evolution  of  hydrogen  is 
just  noticeable  at  the  cathode.  At  the  same  time  the  cathode  solution 
is  powerfully  stirred.  During  the  operation  it  is  advisable  to  keep  the 
temperature  of  the  bath  at  about  20  deg.  C.  The  reduction  is  carried 
out  until  a test  of  the  cathode  liquid  proves  there  is  no  further  nitric  acid 
in  it.  'The  resulting  hydroxylamine  is  then  isolated  from  the  reaction 
liquid  as  a sulphate  or  hydrochloride  by  any  convenient  method. 

Example  II. 

In  carrying  out  this  example  the  same  steps  are  employed  as  in 
example  1 , with  the  exception,  however,  that  the  cathode  chamber  is 
provided  with  6 kilograms  of  hydrochloric  acid  (25  per  cent  solution). 
It  is  preferable  to  employ  a tin  cathode  or  equivalent  cathode  for  this 
example,  or  if  a cathode  of  indifferent  material  is  used,  then  some  spongy 
tin  should  be  added  to  the  bath  in  the  proportion  of  about  1 0 grams  per 
litre. 


Lumiere  and  Seyewetz.  .Monit.  Scient.  vol.  17,  page  109,  1903. 

Trioxymethylene  and  pyrogallol  in  molecular  proportions  are  found 
to  develop  energetically. 

Mctol  is  prepared  in  a similar  manner. 

22 


Luttke  and  Arndt.  French  patent  347396,  Oct.  25,  1904. 

To  400  c.c.  water  add  144.5  grams  para  amidophenol  hydrochl- 
oride and  1 20  grams  potassium  bisulphite,  to  this  solution  is  added 
1 00  grams  of  a 40  per  cent  solution  of  formic  aldehyde.  After  a time 
a crystalline  mass  will  separate  out  of  the  solution. 

Lumiere  and  Seyewetz.  Chem.  Centralb.  vol.  1,  page  412,  1905. 

An  organic  hydrosulphite  of  aniline,  ortho  and  para-toluidin, 
xylidin,  para-phenlenediamine,  di  and  triamidophenol  and  diamidore- 
sorcin  has  been  tried  as  developers. 

AGFA  Co.  German  patent  166799  Mar.  2,  1905. 

Para-oxyphenyl  glycinamide  is  made  by  the  action  of  chlorace- 
tamide  on  para-amidophenol. 

AGFA  Co.  British  patent  9537  May  5,  1905. 

Para-oxy-phenylglycinamide  OH  C®H^  NH  CH^  CO  NH^ 
develops  energetically  with  caustic  and  carbonate  alkalies. 

Sobering.  British  patent  20050  Sept.  7,  1907. 

It  has  been  found  that  the  condensation  products  from  the 
aromatic  aldehydes  and  para-amidophenol  can  easily  and  promptly  be 
reduced  in  acid  or  alkaline  solution,  and  that  in  this  way  aralkyl  para- 
amidophenol  is  obtained,  which  possesses  excellent  developing  properties. 

Example  /. 

Preparation  of  benzyl  para-amidophenol. 

Dissolve  30  grams  benzal  para-amidophenol  (Ber.  vol.  25,  page 
2753,  1892)  in  an  excess  caustic  soda  and  then  15  grams  zinc  dust 
is  added.  After  8 hours  continuous  stirring  the  yellow  appearance 
disappears  slowly,  the  reduction  is  completed  and  the  mixture  is  a light 
grey.  Whilst  slowly  cooling  so  much  acid  is  added  as  to  render  the 
sodium  hydroxide  neutral,  the  liquid  is  then  drained  off  and  the  solid 
precipitate  extracted  by  ether.  After  the  distillation  of  the  ether  the 
new  base  remains  and  may  be  obtained  pure  by  recrystallisation  from 
50  per  cent  methyl  alcohol. 

Benzyl  para-amidophenol  melts  at  89  deg.  C.  It  dissolves  with 
difficulty  in  water,  ligroin  and  alkaline  carbonates,  but  is  readily  soluble 
in  alcohol,  benzene,  and  caustic  alkalies.  Its  hydrochloride  is  easily 
soluble  in  hot  water  and  not  so  readily  in  cold  water,  whilst  the  acetate 
is  easily  soluble  in  cold  water. 


23 


Example  II. 

TTie  reduction  can  also  be  carried  out  in  the  following  manner: 
Dissolve  1 0 grams  benzal  para-amidophenol  in  a mixture  of  60  c.c. 
alcohol,  20  c.c.  glacial  acetic  and  20  c.c.  water  and  boil  the  whole 
together  with  zinc  dust  in  a closed  vessel  fitted  with  a reflux  condenser. 
A slight  amount  of  hydrogen  always  escapes.  After  7 hours,  add  a 
further  2 grams  zinc  dust  and  1 0 c.c.  glacial  acetic  acid  and  boil  for 
another  5 hours.  If  the  alcohol  is  now  evaporated  and  the  whole  cooled, 
mixed  with  some  animal  charcoal,  well  shaken  and  filtered,  the  clear 
filtered  product,  when  sodium  chloride  is  added,  gives  benzyl  para- 
amidophenol  hydrochloride. 

Example  III. 

In  the  same  way  other  condensation  products  from  aromatic  alde- 
hydes and  para-amidophenol  can  easily  be  reduced.  Anisyl-para- 
amidophenol  (methoxy-benzyl -para-amidophenol)  is  best  obtained  in 
the  following  way. 

Stir  12  gram.s  anisylidene-para-amidophenol  (Ber.  vol.  25,  page 
2754,  1 892)  with  40  c.c.  dilute  sodium  hydroxide  (about  1 5 per  cent) 
and  1 5 c.c.  alcohol  and  then  again  for  5 hours  with  6 grams  zinc  dust 
at  60  deg.  C.  Then  the  mixture  is  warmed  and  filtered.  The  sodium 
compound  of  the  methoxybenzyl-para-amidophenol  separates  on  cooling 
as  flakes  with  a golden  color.  The  compound  is  drained  off  and  dis- 
solved in  water.  This  solution  when  neutralized  with  hydrochloric  acid 
gives  the  free  base,  v/hich  when  recrystallised  from  50  per  cent  methyl 
alcohol,  melts  at  1 02  to  1 03  deg.  C. 

This  base  itself  has  a similar  solubility  as  benzyl-para-amidophenol, 
its  salts  are  much  more  easily  soluble. 

Example  IV. 

Salicyl-para  - amidophenol  ( ortho-oxy-benzyl-para-amidophenol  ) 
can  be  produced  in  a similar  way,  using  oxybenzylidene-para-amido- 
phenol  (Ber.  vol.  25,  page  2754,  1892)  and  melts  when  recrystallised 
from  benzene,  at  122  to  1 23  deg.  C.  The  base  dissolves  with  difficulty 
in  water,  but  dissolves  with  ease  in  methyl  or  ethyl  alcohol,  more  so  in 
hot  benzene,  with  difficulty  in  cold  benzene.  The  salts  are  easily  soluble 
in  water  and  can  be  precipitated  from  the  aqueous  solution  by  sodium 
chloride.  The  precipitate  is  at  first  an  oily  mass,  which,  however,  soon 
sets. 

Grar.dmougin.  Jour.  pr.  Chem.  (II),  vol.  76,  page  126,  1907. 

Pafa-hydroygazobenzene  is  dissolved  in  a slight  excess  of  dilute 
sodium  hydroxide,  to  this  solution  is  added  sodium  hyposulphite  until 

24 


it  is  decolorized,  the  aniline  is  driven  over  with  steam,  the  liquid  filtered 
and  on  cooling,  para-amidophenol  crystallizes  out. 

Vida!.  French  patent  391465  and  391466  Aug.  29,  1907. 

Add  188  grams  of  phenol  to  1 08  grams  of  para-phenylenediamine 
in  5 litres  of  water,  with  time  a pearly  scale  deposits  on  cooling. 

AGFA.  Co.  British  patent  4044  Peb.  22,  1908. 

Para  chloropheuol  when  heated  with  ammonia  or  with  a primary 
amine  of  the  fatty  series  in  the  presence  of  a catalyst,  the  halogen  is 
eliminated  and  an  amido  group  or  an  alkyl  amido  group  is  substituted 
therefor.  Thus  for  instance  from  para  clilorophenol  with  ammonia, 
para-amidophenol  is  obtained  ; by  the  action  of  monomethylamine  on 
para  chlorophenol,  mono-raethyl-para  amidophenol  is  formed. 

Example  I. 

Pleat  50  parts  of  para  chlorophenol  together  with  370  parts  of  a 
concentrated  solution  of  ammonia  (25  per  cent  strength)  and  8 parts 
copper  sulphate  in  an  autoclave  for  12  hours  to  140  deg.  C.  From 
the  mass  produced,  which  is  mixed  with  hydrochloric  acid  until  acid 
reaction  occurs,  the  unaltered  para  chlorophenol  is  removed  by  distilla- 
tion. From  the  residue  the  para-amidophenol  is  obtained  in  any  suitable 
manner,  for  instance  by  ad/ding  sodium  carbonate  and  some  sodium 
sulphite,  whereby  the  free  base  is  separated;  it  is  isolated  by  draining 
and  drying  in  a vacuum. 

Example  II. 

Mix  1 30  parts  of  para  chlorophenol  with  270  parts  of  an  aqueous 
solution  of  monomethylamine  (33  per  cent  strength)  and  2 parts  copper 
sulphate  and  the  mass  produced  is  heated  m an  autoclave  to  1 35  deg. 
C.  for  1 0 hours.  The  unaltered  para  chlorophenol  is  then  removed  by 
distillation,  sulphuric  acid  having  previously  been  added  to  the  mass  to 
render  it  acid.  From  the  residue  in  the  still  the  monomethyl-para 
amidophenol  may  be  separated  in  a form  of  its  sulphate  by  concentrating 
the  liquid;  the  sulphate  is  then  isolated  in  the  usual  manner. 

Jennot  & Bremner.  British  patent  15657  July  23,  1908. 

Wtih  the  addition  of  magnesium  picrate  to  a diamidophenol  solu- 
tion (using  sodium  sulphite)  it  is  possible  to  develop  and  fix  simul- 
taneously in  broad  daylight. 

Claus.  British  patent  11590,  May  17,  1909. 

To  48  parts  of  dinitrochlorbenzene  and  150  parts  of  water  is 
heated  in  a suitable  vessel  and  to  this  mixture  62  parts  of  a sodium 
hydroxide  solution  (70  deg.  Tw.)  added  and  boiled  until  all  of  the 
dinitrochlorbenzene  has  been  converted  to  dinitrophenol. 

25 


Thorpe.  Dictionary  of  App.  Cliem.  vol.  4,  page  182,  1913. 

A concentrated  solution  of  sodium  dichromate  is  gradually  added 
to  a well  cooled  (5  to  10  per  cent)  solution  of  1 part  of  analine  in 
8 parts  of  sulphuric  acid  and  25  parts  of  water.  The  mixture  at 
first  becomes  green,  and  towards  the  end  of  the  operation  is  deep  blue- 
black;;  a further  addition  of  the  dichromate  solution  brings  about  the 
solution  of  the  greater  part  of  the  precipitate,  and  a brown,  turbid  liquid 
is  obtained  containing  quinone  and  quinhydrone,  by  passing  sulphur 
dioxide  through  the  liquid  until  it  smells  of  sulphurous  acid,  the  sus- 
pended matter  is  filtered  off,  and  the  hydroquinone  extracted  from  the 
filtrate  by  means  of  ether;  which  is  subsequently  distilled  off.  The 
yield  of  crude  hydroquinone  under  these  conditions  amounts  to  as  high 
as  85  per  cent. 

In  order  to  purify  the  product  it  is  dissolved  in  the  smallest  possible 
amount  of  hot  water,  the  solution  is  then  boiled  with  animal  charcoal 
and  a little  sulphurous  acid,  filtered  and  allowed  to  cool. 

When  crystallization  is  slow  the  hydroquinone  is  lemon-yellow  in 
color  and  contains  27.2  per  cent  of  water  per  100  per  cent.  But  if 
formed  rapidly,  they  are  very  white  and  takes  up  only  12.8  parts  of 
water. 

Pyrogallol  is  prepared  by  heating  gallic  acid  with  two  or  three 
times  its  weight  of  water  in  a bronze  digester  at  200  to  210  deg.  C. 
for  about  half  an  hour,  a paper  ring  being  placed  between  the  vessel 
and  its  cover  to  allow  the  carbon  dioxide  to  escape.  The  resulting 
solution  of  p3'rogallol  is  boiled  with  animal  charcoal,  filtered  and  con- 
centrated. The  pyrogallol,  crystallizing  out,  is  distilled  under  a pressure 
of  20  to  30  mm.  in  order  to  obtain  it  perfectly  white. 


Fischer.  British  patent  2562  Jan.  31,  1913. 


The  following  compounds  it  is  found  to  develop  the  image  and 
simultaneously  yields  a tone  or  color  to  the  photograph  proper,  the  com- 
pounds used  are: 

phenols:  Idophenols 

-[-phenols:  Indoanilines  and  oxazines 

-[-amines:  Indamines 

-j-thiophenols:  Indothiophenols 

-[-combinations  containing  Azomethine 
-[-  methyl  groups 


para-amidophenols 

para-phenylenediamines 

para-phenylenediamines 

para-phenylenediamines 

para-amidophenols 

para-phenylenediamines 


The  bodies  with  most  difficulty  are  obtained  with  para-phenylene- 
diamine  as  the  developer  and  phenols  or  compounds  with  acid  methylene 
groups  as  coupling  bodies.  The  para-phenylenediamines  comprise  the 
side-chain  homologues,  also  the  substitution  products  of  para-phenylene- 
diamine  in  one  amido  group,  the  other  being  free. 


26 


Example  I. 

Para-phenylenediamine,  para-toluylenediamine,  amido,  chlor, 
monoethyl  and  dimethyl-para-phenylenediamine.  Further,  one  amido 
group  may  be  included  in  a ring  system-para-amidophenylene-piperdine. 
By  phenols  the  side-chain  and  nucleus  homoiogues  and  the  substitution 
products  are  likewise  to  be  understood. 

Example  II. 

Phenols,  cresols,  alpha  napthol,  ortho  amidophenol,  trichlornapthol, 
resorcin-methyl-ether,  alpha-napthol-sulphonic  acid.  The  acid  methy- 
lene compounds  may  be  either  aliphatic  or  aromatic  in  nature. 

Example  III. 

Ethyl-aceto-acetate,  malono-nitrile,  chlor  acetophenone,  diketo- 
hydrindene,  nitrobenzyl-cyanide,  thioindoxyl.  Furthermore,  the  methy- 
lene group  may  be  substituted  when  the  substitutmg  group  is  split  off 
during  the  reaction. 

Example  IV. 

Chlor-ethyl-aceto-acetate,  thioindoxyl-carboxylic  acid.  The  color- 
ing matter  or  dye  produced  in  these  methods  of  development  can  be 
reduced  to  leuco  compounds  which  likewise  possess  developing  properties 
and  also  yield  colored  images  directly  during  the  developing  process  when 
the  oxidation  products  are  soluble  with  difficulty.  In  this  case  also  it  is 
found  that  the  above-mentioned  classes  of  coloring  materials  yield  the 
best  results.  The  developing  properties  of  some  of  these  classes  are 
already  known,  for  example,  the  developer  dioxydiphenylamine  is  a leuco- 
indophenol.  In  this  instance,  however,  only  black  and  white  images  are 
produced,  and  colored  images  result.  It  is  preferable  to  omit  the  admix- 
ture of  sodium  sulphite  or  similar  bodies  when  preparing  the  bath.  The 
employment  of  leuco  bodies  is  likewise  not  advisable,  because  they 
change  easily,  whilst  the  separate  form  of  employment  first  described 
has  the  advantage  that  the  components  can  be  preserved  separately  and 
need  only  be  mixed  immediately  before  development  or  added  when 
developing. 

Vidai.  French  Patent  469537  April  26,  1913. 

The  compound  described  in  French  patent  391465  are  obtained 
by  condensing  aromatic  amines,  hydroxyamines,  or  their  alkyl  derivitives 
with  phenols,  dihydroxy  naphthalenes,  hydroxy-quinolines,  hydroxy 
anthraquinolines  or  dihydroxy-diphenylamines,  especially  in  the  presence 
of  hydrocarbons  (benzene,  etc.).  Their  activity  depends  on  their  con- 
stitution ; thus,  the  product  from  one  part  of  para-phenylenediamine  and 
two  parts  of  phenol  is  a slow  developer,  and  that  from  three  parts  of 
para-phenylenediamine  and  two  parts  of  pyrogallol  is  a rapid  developer. 

27 


Brochet.  British  patent  16938  July  23,  1913. 

Dissolve  one  kilogram  of  para-nitranaline  in  one  kilogram  amylic 
alcohol  in  which  one  per  cent  of  reduced  nickel  is  added.  The  mixture 
I.S  subjected  to  the  action  of  hydrogen  at  1 20  to  1 30  deg.  C.  and  at  a 
pressure  of  ! 0 to  15  kilograms  per  square  cm.  and  agitated  continuously. 
The  reaction  is  very  rapid  and  the  catalyser  is  separated  by  filteration 
and  the  para-phenylenediamine  crystallized  out  on  cooling. 

Para-nitrophenol  may  be  used  in  the  place  of  para-nitranaline  in 
order  to  obtain  the  corresponding  amidophenol. 

AGFA  Co.  British  Patent  18095  Aug.  8,  1913. 

Example  /. 

Boil  together  246  parts  of  4-methyl  amidophenol,  1 10  parts  of 
chloracetic  acid  and  1 000  parts  of  water  from  three  to  four  h-urs. 
From  the  cooled  solution  the  4-oxy-phenyl  methyl  glycine  separates  out. 
It  is  recrystalhzed  from  boiling  water. 

Example  II. 

Dissolve  1 part  of  4-oxy-phenyl  methyl  glycine,  5 parts  of  sodium 
sulphite  and  5 parts  of  potassium  carbonate  in  1 2 parts  of  water.  This 
solution  is  a concentrated  developer  and  is  to  be  diluted  for  use  with 
1 0 to  30  parts  of  water. 

Instead  of  4-oxy-phenyl  methyl  glycine ; 4-oxy-phenyl  ethyl  glycine 
may  be  used. 

Jansen.  Zeit.  Parb.  Ind.  vol.  12,  page  197,  1913. 

Para-phenylenediamine  is  prepared  by  reducing  amidoazobenzene 
or  para-nitro  aniline,  the  former  being  probably  the  cheaper  method. 

Example  /. 

(From  amidoazobenzene) 

The  mixture  of  amidoazobenezene  and  analine  obtained  in  Jansen’s 
method  of  preparation  is  not  separated,  but  the  contents  of  the  lead-lined 
pan  are  blown  into  a cast  iron  reduction  pan  such  as  is  used  for  the 
manufacture  of  aniline,  except  that  a steam  jacket  surrounds  its  lower 
half.  The  pan  is  previously  charged  with  1 00  kilos,  of  ground  iron 
borings,  some  water,  and  about  3 litres  of  hydrochloric  acid  (28  per 
cent) , and  the  mixture  well  stirred.  Reduction  begins  as  soon  as  the 
amidoazobenzene  comes  in  contact  with  the  iron  and  the  temperature 
rises  gradually  to  20  to  40  deg.  Stirring  is  continued  overnight,  and 
next  morning  the  contents  will  have  become  completely  colorless.  The 
batch  is  now  heated  by  means  of  the  steam  jacket,  and  steam  is  also 
blown  through  the  hollow  stirrer  and  the  excess  of  aniline  distilled  off. 
The  solution  in  the  pan  is  allowed  to  settle,  the  clear  solution  pumped 

28 


through  the  filter  press,  and  the  iron  sludge  washed  out  with  hot  water. 
The  solution  so  obtained  contains  on  the  average  75  kilos,  of  para- 
phenylenediamine,  which  is  about  85  per  cent,  of  the  theoretical  quan- 
tity reckoned  from  the  sodium  nitrite  used. 

Example  II. 

(From  para-nitroaniline) 

In  this  case  no  condenser  is  required  to  be  fitted  to  the  reduction 
pan,  but  the  latter  must  have  a flue  fitted  to  the  lid  through  which  the 
steam  may  escape.  Also  no  steam  jacket  is  'required.  A large  funnel, 
closed  with  a wooden  plug,  is  fitted  on  the  lid,  above  which  is  also  a 
water  tap.  The  pan  is  charged  with  200  kilos,  of  ground  iron  borings, 
water,  and  9 litres  of  hydrochloric  acid  (26  per  cent.),  so  that  the 
bottom  wing  of  the  agitator  is  just  covered,  and  the  mixture  is  boiled. 
Steam  is  then  shut  off  and  200  kilos,  of  para-nitroaniline  are  added 
slowly,  each  addition  being  made  after  the  cessation  of  the  vigorous 
reaction  caused  by  the  previous  one.  Care  must  be  taken  that  the 
mixture  is  not  caused  to  boil  over  through  too  quick  addition.  Should 
this  tend  to  occur,  it  may  be  corrected  by  adding  cold  water  from  the 
tap  above  the  pan.  It  is  necessary  indeed,  to  allow  a slow  stream  of 
water  flow  into  the  pan  to  make  up  for  the  water  lost  as  steam.  When 
all  the  para-nitroaniline  is  in,  the  liquid  is  yellow;  14  litres  of  hydro- 
chloric acid  (28  per  cent.),  are  added  and  stirring  is  continued.  No 
vigorous  reaction  takes  place,  but  the  yellow  color  soon  vanishes.  When 
a drop  of  the  liquid,  placed  on  filter  paper,  gives  a colorless  rim,  the 
reduction  is  finished.  Twenty-five  kilos,  of  sodium  carbonate  are  now 
added  slowly,  so  that  the  solution  has  a faintly  alkaline  reaction  to 
phenolphthalein,  and  the  batch  is  boiled  for  ten  minutes  and  allowed  to 
settle.  The  clear,  hot  liquid  is  pumped  through  the  filter  press  and  the 
iron  sludge  washed  out  with  hot  water.  The  solution  is  evaporated 
until  the  base  crystallizes  out  on  cooling.  The  yield  is  90-95  per  cent, 
of  the  thoretical,  and  the  product  is  of  a high  degree  of  purity.  If  neces- 
sary, it  can  be  distilled  in  a vacuum. 

Wolffenstein  and  Bolters.  Ber.  vol.  46,  page  586,  1913. 

Dinitrophenol  is  obtained  direct  from  benezene  by  mixing  1 20 
grams  of  benezene  with  20  grams  mercuric  nitrate,  and  the  mixture  is 
treated  with  270  grams  nitrogen  tetraoxide  and  allowed  to  remain  for 
some  days  at  the  ordinary  temperatures,  or  the  same  weight  of  benzene 
is  treated  with  10  grams  of  mercuric  nitrate  and  500  grams  of  50  per 
cent,  nitric  acid;  50  grams  of  nitric  oxide  are  added,  and  the  mixture 
is  stirred  and  heated  to  50  deg. 

Merck.  German  patent  260234  1913. 

Hydroquinone  is  treated  with  a mono-alkylamine  (methyl 
chloride)  and  a reducing  agent.  This  is  heated  to  200  to  250  deg.  for 
about  5 to  20  hours  to  form  methyl-para-amidophenol. 

29 


Lumiere  and  Jougla.  British  patent  1795  Jan.  22,  1914. 

Mono-chlorhydroquinone  is  substituted  for  the  hydroquinone  in 
the  British  patent  7163,  Mar.  27,  1903. 

Meister,  Lucius  and  Bruning.  German  patent  284423  Feb.  24,  1914. 

By  development  with  a mono  alkyl  ether  of  dihydroxy  napthalene 
and  treating  the  developed  image  with  a reducing  agent  (Farmer’s  re- 
ducer) a blue  image  will  remain. 

Lumiere  and  Seyewetz.  Bull.  Soc.  Franc.  Photo,  vol.  6,  page  181, 

1914. 

By  the  introduction  of  a methyl  group  in  hydroquinone  results  in 
an  increase  of  developing  power.  On  the  other  hand,  the  introduction 
of  nitro  or  sulphonic  groups  causes  a considerable  decrease  of  develop- 
ing power,  dinitroquinol  possessing  no  developing  properties.  When  a 
halogen  and  a sulphonic  group  are  present  together  in  the  hydroquinone, 
products  are  obtained  which  are  more  active,  quinolsulphonic  acid  but 
less  active  than  hydroquinone  itself,  depending  of  course  on  the  relative 
positions  of  the  substituent  groups. 

Pellizzari.  Annali  Chim.  vol.  2,  page  129,  1914. 

Para-amidophenol  acetone  bisulphite  (OH  NH®  SO* 

(CH*)^CO)  is  obtained  by  suspending  100  grams  of  para-amidophenol 
in  200  c.c.  of  water,  passing  in  a current  of  sulphur  dioxide  and  adding 
gradually  50  c.c.  of  acetone.  When  the  solution  is  clear,  a further 
20  c.c.  of  acetone  is  added.  The  compound  separates  in  minute  glisten- 
mg  crystals.  The  corresponding  raethyl-para-amidophenol  is  prepared 
in  a similar  manner. 

Ufer,  Driebrodt  and  Rohler.  British  patent  14714  Oct.  18,  1915. 

Ferrous  oxalate  is  made  more  permanent  by  the  addition  of  neutral 
salts  of  a mono-or  poly  hydroxy  carboxylic  acid  of  which  the  glycolates 
are  particularly  valuable. 

Society  of  Chemical  Industry.  British  patent  18081  Dec.  28,  1915. 

Example  I. 

The  electrolytic  vessel  is  a lead  cylinder  which  serves  as  the  anode. 
In  it  is  placed  a porous  cylinder  containing  a copper  cathode  in  the  form 
of  a hollow  perforated  cylinder,  and  within  this  is  a suitable  stirrer.  One 
or  more  rods  of  lead  dip  into  the  cathode  chamber.  The  anode  chamber 
is  charged  with  20  per  cent  sulphuric  acid  and  the  cathode  chamber 
with  25  litres  of  sulphuric  acid  (15  deg.  Be.)  and  6 kilos  of  nitro- 
benzene, which  is  kept  in  the  form  of  an  emulsion  by  means  of  the 
stirrer.  The  electrolysis  is  carried  on  at  80  to  95  deg.  with  a current 
of  about  3 amperes  per  square  decimeter  of  cathode  surface  at  3-3  J/2 
volts  until  all  the  nitro-benzene  has  disappeared.  Milk  of  lime  is  now 

30 


added  and  the  aniline  distilled  off  with  a current  of  steam.  The  re- 
maining hot  solution  of  para-amidophenol  is  filtered  from  calcium  sul- 
phate and  evaporated  to  crystallization.  The  yield  of  para-amido- 
phenol is  about  50  per  cent  of  the  weight  of  nitrobenzene  used  (about 
56  per  cent  of  the  theoretical),  and  aniline  is  produced  to  the  extent 
of  about  20  per  cent  of  the  weight  of  para-amidophenol  formed.  If 
arsenic  is  present  (for  example,  in  the  sulphuric  acid)  the  amount  of 
aniline  obtained  will  fall  to  about  10-15  per  cent  of  the  weight  of  para- 
amidophenol.  Instead  of  the  arrangement  described,  the  cathode  may 
be  of  lead  and  a copper  rod  may  be  suspended  in  the  cathode  chamber, 
or  copper  sulphate  may  be  added  to  the  chamber  and  renewed  from 
time  to  time. 

Example  II. 

Instead  of  the  copper  cathode  described  in  example  1 , a lead 
cathode  is  used  and  instead  of  the  lead  rods  there  are  introduced  into 
the  cathode  chamber  about  20  grams  of  metallic  bismuth.  The  elec- 
trolysis and  *^he  working  up  of  the  products  are  conducted  as  in  example 
1.  Para-amidophenol  is  obtained  in  yield  of  about  50  per  cent  of  the 
weight  of  the  nitrobenzene  used  and  the  aniline  produced  amounts  to 
about  1 4 per  cent  of  the  weight  of  the  para-amidophenol. 


Harger.  Jour.  American  Chem,  Soc.  Feb.  1919  page  272. 

A small  steel  autoclave  ( 1 00  c.c.  capacity)  heating  equimolar 
quantities  of  hydroquinone  and  10  N aqueous  methylamine  for  20 
hours  at  220  to  250  deg.,  but  the  yield  of  the  metol  base  was  very 
small  and  much  tarry  material  resulted.  This  result  was  thought  to  be 
due  to  the  catalytic  action  of  the  iron,  so  the  following  batch  was 
carried  out  in  glass.  However,  later  experiments  indicate  that  the  iron 
has  no  ill  effect. 

The  second  experiment  was  more  successful,  this  was  done  by 
dissolving  20  grams  of  hydroquinone  in  20  c.c.  of  N aqueous  methyl- 
amine  (an  evolution  of  heat  taking  place  when  the  two  were  mixed). 
This  was  then  heated  for  3 hours  at  a temperature  of  200  deg.  Upon 
cooling,  the  contents  of  the  autoclave  were  poured  into  sulphuric  acid 
(1  :20).  The  mixture  was  boiled  to  insure  solution  and  made  up  to 
one  litre.  This  was  then  concentrated  to  1 00  c.c.  and  cooled  on  ice, 
and  the  resulting  crystals  collected  on  a Buchner  funnel,  washed  with 
alcohol,  dried  and  weighed.  Analysis  showed  that  they  were  practically 
pure  metol.  It  was  of  a grayish  color  and  on  recrystallization  from 
boiling  water  containing  one  gram  of  decolorizing  charcoal  for  each  1 00 
c.c.  of  water.  The  yield  is  5 per  cent. 

31 


CHAPTER  ir. 


DYE  SENSITIZERS 

Jacobsen.  United  States  patent  257717  May  9,  1882'. 

Quinoline  Red. 

When  equal  quantities  of  quinoline  and  benzotrichloride  are 
heated  to  1 30  deg.  C.  the  mixture  thickens  gradually  and  assumes  a 
red  color.  After  heating  for  some  hours  (for  the  purpose  of  withdraw- 
ing the  base)  the  melt  not  acted  upon  is  to  be  extracted  with  cold  water 
and  the  residue  afterward  exhausted  by  a large  excess  of  boiling  water. 
The  dark-red  solution  on  the  addition  of  an  alkali,  yields  a reddish- 
brown  amorphous  precipitate  of  a color.  This  is  purified  by  dissolving 
it  in  an  acid  solution  (acetic  or  oxalic)  and  once  more  precipitated  by 
an  alkali.  Its  hydrochloride  is  readily  soluble  in  water. 

Jacobsen.  United  States  patent  290585  Dec.  18,  1883. 

Quinoline  Yellow. 

Fuse  together  10  parts  quinaldine,  12  parts  phthalic  anhydride 
and  1 part  zinc  chloride  from  190  to  210  deg.  C.,  and  boil  out  the 
resulting  melt  with  dilute  hydrochloric  acid.  This  is  only  soluble  in 
alcohol,  in  order  that  it  may  be  used  to  advantage  in  actual  practise  it 
must  be  soluble  in  water,  for  this  reason  1 part  of  the  dye  is  heated 
With  3 or  4 parts  of  sulphuric  acid  until  a sample  of  it  will  dissolve  in 
water,  after  which  the  remainder  is  to  be  poured  into  water  containing 
milk  of  lime,  the  sulphate  of  lime  is  filtered  from  the  dyestuff.  With 
sodium  carbonate  it  is  converted  into  its  sodium  salt. 

Hoffman.  United  States  patent  316036  Apr.  21,  1885. 

Napthol  Green. 

Dissolve  27.5  kilos  sodium  nitroso  a-naphthol  monosulphonate  in 
100  litres  of  hot  water.  To  the  cool  solution  is  added  20  litres  of  dis- 
solved iron  perchloride  (containing  5 kilos  Fe^  CF).  The  yellow 
brownish  solution  becomes  dark  brown  and  finally  deep  black.  After 
several  hours  standing  the  excess  of  iron  is  precipitated  by  an  alkali  and 
the  filtered  solution  showing  a green  color,  is  evaporated,  or  precipitated 
with  sodium  chloride. 


32 


Naphthol  green  completely  absorbs  the  red  and  passes  ultra  violet. 
It  is  a permanent  color. 

Ziegler.  United  States  patent  324630  Aug.  18,  1885. 

I Tartrazine. 

Mix  together  1 0 parts  sodium  bioxytartrate  and  1 6 parts  water, 
heat  up  to  40  deg.  C.,  then  add  13  parts  hydrochloric  acid  (sp.  gr. 
1.18).  The  solution  thus  obtained  is  mixed  with  20  parts  phenyl 
hydrazine  sulphonic  acid  (Ann.  Chem.  Pharra.  vol.  190  page  76) 
previously  dissolved  in  60  parts  water  and  1 0 parts  sodium  hydroxide 
solution  containing  30  per  cent  of  solid  sodium  hydroxide.  The  mixture 
is  then  heated  to  80  deg.  C.,  up  to  one  hour,  allow  to  cool  in  order 
to  separate  the  dyestuff.  The  precipitate  thus  obtained  is  then  filtered, 
pressed  and  dried. 

Weinberg.  United  States  patent  464538  Dec.  8,  1891. 

Formyl  Violet. 

Example  J. 

Heat  together,  50  kilos  methyl  (or  ethyl)  benzyl  aniline  sulpho.nic 
acid  on  the  water-bath  with  3 kilos  formic  aldehyde.  After  24  hours 
the  reaction  is  terminated.  On  cooling,  the  dimethyl  (ethyl)  dibenzyl 
diphenyl  methane  disulphonic  acid  separates  from  the  solution.  Sixty 
kilos  of  this  acid  is  dissolved  in  2000  litres  of  water,  1 2 kilos  dimethyl- 
aniline  (or  1 5 kilos  diethylaniline)  and  20  kilos  potassium  bichromate 
is  added  and  heated  for  24  hours  from  40  to  50  deg.  C.  The  chrom- 
hydrate  is  separated  by  filtration  and  from  the  violet  solution  the 
tetramethyl  (ethyl)  dibenzyl  triamido  triphenyl  carbinol  disulphonate 
is  precipitated  by  sodium  chloride. 

Example  II. 

Dissolve  29  kilos  ethyl  benzylaniline  sulphonic  acid  in  60  kilos 
sulphonic  acid  containing  50  per  cent  H-SO^.  To  this  solution  12 
kilos  dimethylaniline  and  then  3 kilos  formic  aldehyde  in  a concentrated 
aqueous  solution  is  added,  and  heated  for  36  hours  to  about  80  deg.  C., 
and  diluted  with  water.  The  diraethyl-ethylbenzyl  diamido  diphenyl- 
methane  and  mono  sulphonic  acid  which  dissolves  with  difficulty  in  water 
separates  entirely.  Fifty  kilos  of  this  acid  is  dissolved  in  5000  litres 
of  water  of  50  deg.  C.,  together  with  30  kilos  benzyl  ethylaniline 
sulphonic  acid.  It  is  oxidized  with  20  kilos  potassium  bichromate  and 
heated  24  hours  from  50  to  60  deg.  C.  The  thus  obtained  violet  dye- 
stuff is  identical  with  that  of  the  first  example. 

33 


Leaper.  Materia  photographica 


Quinoline  Blue,  Cyanin. 

Mix  together  60  parts  glycerin,  1 9 parts  aniline,  1 2 parts  nitro- 
benzene and  50  parts  sulphuric  acid,  this  is  heated  for  three  hours  at 
1 30  deg.  C.  (the  flask  must  be  provided  with  an  inverted  condenser) . 
At  the  end  of  this  period  the  condenser  is  removed  and  the  product 
heated  for  3 hours,  or  until  no  fumes  are  forthcoming.  The  liquid  is 
finally  poured  over  an  excess  of  lime  contained  in  a hard  glass  retort 
and  distilled.  The  mixture  of  quinoline  and  aniline  so  prepared  is 
then  redistilled  in  a retort  provided  with  a thermometer,  the  distillation 
being  stopped  when  the  thermometer  indicates  1 90  deg.  C.  By  this 
means  the  quinoline,  which  boils  at  240  deg.  C.  is  left  behind.  This 
is  then  fused  with  amyl  iodide  and  potassium  hydroxide  and  the  fused 
mass  treated  with  alcohol,  which  dissolves  out  the  quinoline  blue,  from 
which  solution  it  can  be  obtained  by  evaporation. 

Quinoline  blue  is  used  as  a red  sensitizer  and  is  very  unreliable  in 
view  of  the  fact  that  it  gives  spots,  fog  and  lacks  in  density  of  the 
negatives. 

Isokol  is  a mixture  of  Quinoline  blue  and  one  of  the  red  sensitizers 
and  gives  sensitiveness  for  all  the  colors  from  red  to  blue  and  compares 
exactly  with  Pinachrome. 

Miethe  and  Traube.  United  States  patent  724.311  Mar.  31,  1903. 

Pinacyanol. 

Mix  together  1 1.7  parts  of  quinoline,  13.1  parts  quinaldine  and 
15.6  parts  ethyl  iodide,  the  mixture  is  boiled  and  the  crystals  which 
separate  out  are  purified  by  recrystallization  from  alcohol.  The  products 
thus  obtained  are  mixed  in  molecular  proportions  and  heated  in  boiling 
alcohol  with  a solution  of  potassium  hydroxide.  The  alcohol  being 
partly  evaprated,  the  due  crystallizes  out  and  is  purified  in  the  usual  way. 

Harrison  and  Bottomly.  Jour.  Soc.  Dyers  and  Colorists,  vol.  33, 
page  88,  1917. 

Pinacyanol. 

Dissolve  30  parts  quinaldine  ethyl  iodide  in  hot  alcohol  mixed 
with  1 0 parts  formaldehyde  (40  per  cent  solution)  and  1 5 parts  of 
sodium  hydroxide  ( 1 6 per  cent  solution)  and  heated  on  the  water  bath 
for  a half  hour.  After  cooling  the  solution  is  diluted  with  500  parts 
of  water,  when  the  Pinacyanol  separates  out  completely,  and  after 
drying  it  is  purified  by  recrystallization  from  hot  wood  alcohol.  In 
place  of  the  latter  solvent  pyridine  may  also  be  employed. 

Pinacyanol  is  a panchromatic  sensitizer  and  does  not  show  great 
green  sensitiveness,  for  this  reason  it  is  generally  used  as  a red  sensitizer. 

34 


Orthochrome  T. 


Dissolve  30  grams  para-toluquinaldine  ethyl  iodide  in  800  c.c. 
of  alcohol  and  mix  while  hot  with  a solution  of  6 grams  potassium 
hydroxide  in  alcohol.  The  reaction  takes  place  very  quickly  and  is 
finished  within  a few  minutes.  The  orthochrome  T is  then  precipitated 
by  the  addition  of  a 1 0 per  cent  solution  of  sodium  chloride,  washed 
with  water,  dried  and  extracted  with  ether  to  remove  any  resinous  matter 
which  is  likely  to  be  present.  The  dye  may  also  be  precipitated  with 
ether  and  purified  by  recrystallization  from  dilute  alcohol. 

This  dye  sensitizes  plates  to  the  green  end  of  the  spectrum. 

Meyer.  United  States  patent  890588  June  9,  1908. 

Quinoline  Yellow. 

Fuse  together  1 77.5  parts  para-chloro  quinaldin  (obtained  by 
treating  para-chloro  aniline  with  acetaldehyde  and  hydrochloric  acid) 
and  1 48  parts  phthalic  anhydride  to  2 1 0 deg.  C.  After  5 to  6 hours 
the  reaction  is  complete.  The  chloro  quinophthalone  is  washed  with  a 
little  alcohol  and  dried.  It  is  a yellow  powder  and  soluble  in  alcohol 
with  a yellow  color. 

Mix  1 part  of  the  new  chloro-quinophthalone  with  3 parts  fuming 
sulphuric  acid  (38  per  cent  of  SO^).  The  mixture  is  then  slowly 
heated  from  80  to  90  deg.  and  kept  at  this  temperature  from  4 to  5 
hours.  Subsequently  the  product  of  the  reaction  is  poured  into  1 0 times 
its  quantity  of  water  and  from  the  liquid  thus  obtained  the  sulphonic  acid 
is  precipitated  by  the  addition  of  sodium  chloride. 

The  sodium  salt  of  this  sulphonic  acid  is  a yellow  powder  soluble 
in  concentrated  sulphuric  acid  with  a yellow  color  and  soluble  in  water 
with  a yellow  color  which  turns  reddish-yellow  on  addition  of  dilute 
alkalies. 


35 


Wein.  American  Annual  of  Photo,  page  265,  191S. 


CHAPTER  III. 

PHYSICAL  AND  CHEMICAL  CHARACTERISTICS  OF  DEVELOPERS 

The  number  of  “organic  compounds”  used  as  photographic  developers 
has  increased  to  such  a large  extent,  and  the  need  of  a summary  of 
the  general  characteristic  reaction  of  these  substances  led  the  writer  to 
investigate  these.  His  observations  are  given  in  routine  form. 

The  developers  reviewed  in  this  paper  are  only  those  that  have  be- 
come popular  and  in  use  ever}'^  day. 

In  making  tests,  the  investigator  is  advised  to  do  this  in  the  sys- 
tematic manner  given  ; viz. ; — commercial  name ; chemical  name ; con- 
stitution formula,  crystalline  formation,  melting  point,  solubility,, 
behavior  to  alkalies,  acids,  oxidizing  agents,  and  milk  enzymes. 

The  chief  commercial  developers  may  be  classified  into ; — Para- 
midophenol,  Diamidophenol.  Methyl-paramidophenol,  Methyl-ortho- 
amidophenol,  Pyrogallol,  Pyrocatechin,  Hydroquinone  (and  haloid  sub- 
stitution products)  jMonobrom  or  Chlor-hydro  quinone. 

Amido-hydrocarbons ; — Paraphenylenediamine. 

Naphthalehe  salts: — Eikonogen. 

Complex  amido  acids  : — Glycin. 

Nearly  all  photographic  developers  give  a more  or  less  cojbred 
solution  with  raw  milk  that  has  not  been  heated  above  75“  C.,  in 
presence  of  hydrogen  peroxide.  This  is  due  to  the  “enzymes”  in  the 
raw  milk  action  as  “carriers”  of  oxygen,  and  giving  a coloration 
which  is  the  result  of  oxidation.  The  enzymes  are  destroj'ed  at  a 
temperature  above  75“  C.  Two  developers  (ortol  and  paraphenylene- 
diamine) give  such  a decided  reaction  witli  raw  milk  that  they  can  be 
used  for  detecting  aS  little  as  I per  cent,  of  raw  milk  in  boiled  milk. 
With  boiled  milk  there  is  no  immediate  coloration ; a little  coloration 
is  apt  to  occur  later,  but  this  is  negligible.  The  reaction  is  prevented 
by  caustic  alkalies,  and  especially  by  the  presence  of  a little  sulphite 
or  metabisulphite.  In  this  case  the  sulphite  must  be  decomposed  by 
'well,  boiling  with  a little  hydrochloric  acid  and,  neutralizing.  MetoL 
paramidophenol,  pyrocatechin,  and  amidol  give  a more  or  less  deep 
“cafe-au-lait”  color  with  raw  rrlilk.  Glycin,  hydroquinone,  adurol,  aud 
eikonogen  give  no  immediate  coloration  w'ith  raw  milk,  but  the  milk 
becomes  gradually  of  a pinkish  or  salmon  tint.  There  is  no  coloration 
with  boiled  milk  in  a similar  time.  Pyrogallol  gives  an  immediate 
brownish-yellow. 

Some  developers  yield  on  oxidation  with  acid-bichromate  a quinone, 
which  is  usually  a deep  yellow,  not  very  soluble,  volatile  substance, 
with  an  odor  which  is  very  characteristic  and  pungent,  especially  whep 
the  solution  is  boiled.  Other  developers  yield  no  quinone.  Adurol 
produces  a. chloro-  or  bromo-quinone,  but  the  smell  is  similar  to  that  of 
ordinary  quinone.  In  order  to  determine  whether  the  solid  developing 
substance  is  a simple  developer  or  not,  test  for  the  presence  of  sulphite 
and  carbonate.  Carbonate,  however,  is  not  likely  to  be  found.  If 
sulphite  is  present,  decompose  it  by  heating  wdth  hydrogen  peroxide 
and  well  boiling  to  expel  sulphur  dioxide,  then  neutralize  with  sodium 
carbonate.  The  resulting  solution  will  contain  the  developer  together 
with  a little  sulphate  and  chloride,  w'hich  will  only  interfere  with  the 
solubility  and  lead  acetate  tests.  The  solution  may  then  be  examined 
by  the  system  described  .below.  After  the  presence  of  certain  de- 
velopers has  inferred  they  may  be  isolated  with  suitable  solvents  and 


36 


confirmed.'  If  Sulphite  and  carBdnate  are  absent,  recrystallize  a little 
of  the  substance  on  a slide  and  examine  microscopically  to  see  if  the 
crystals  are  all  similar  or  not.  If  different  crystalline  substances  are 
noticed,  try  the  effect  of  solvents  on  the  mixture,  and  submit  the 
residues  to  examination  by  the  system  described  lielow.  It  is  as  well  to 
remember  that  there  are  crystalline  combinations  (weak  chemical 
compounds)  of  such  substances  as  metol  and'  hydroquinone,  but  they 
are  readily  decomposed  when  boiled  with  water  in  the  presence  of  a 
ilittle.acid  or  alkali.  If  the  developer  is  in  the  liquid  form  sulphite  is 
always  present. 

In  performing  the  ferric  chloride  test  Liquor  Ferri  Perchloridi 
should  be  used.  If  a very  dilute  ferric  solution  is  used  the  developer 
will  be  in  excess,  and,  being  a powerful  reducer,  will  reduce  the  ferric 
salt  to  the  ferrous  condition,  so  that  the  reactions  with  a ferrous  sail 
are  obtained.  For  instance,  pyrocatechin  gives  two  different  reactions 
according  as  the  ferric  chloride  is  in  deficiency  or  excess. 

Note. — ^The  word  “developer'’  is  restricted  to  the  active  reducing 
agent. 


Developers  Yielding  a Quinone  iejith  Acid-Bichromate) 

Note. — If  there  is  any  doubt  as  to  the  presence  of  quinone  on  heating 
the  substance  with  acid-bichromate  solution,  drop  one  or  two  crystals 
of  hydroquinone  into  the  boiling  mixture,  and  the  odor  of  quinone 
will  at  once  be  evident  for  comparison. 

To  the  neutral  or  slightly  acid  concentrated  solution  of  the  de- 
veloper add  a few  drops  of  caustic  soda  solution.  A crystalline  pre 
cipitate  soluble  in  excess  indicates  paramidophenol  (deep  violet  on 
solution  iii  alkali)  or  glycin  (no  color  on  solution  in  alkali). 

Caustic  soda  gives  no  precipitate.  This  indicates  either  metol,  hydro- 
quinone, or  adurol. 

Note. — If  the  solution  is  extremely  concentrated  or  saturated  with 
sodium  chloride  the  base  of  metol  ' is  apt  to  be  precipitated,  but  the 
crystals  are  flocculent  and  not  glistening  like  paramidophenol  or  glycin 
They  readily  dissolve  on  adding  a few  drops  of  water. 

(a)  The  substance  gives  a nitrogenous  odor  when  heated  in  a sub 
limation  tube,  and  is  not  shaken  out  by  ether  from  an  acid  solution 
This  indicates  metol. 

(b)  The  substance  sublimes  and  gives  no  nitrogenous  odor  in  a 
sublimation  tube;  it  is  readily  shaken  out  by  ether  from  an  acid 
solution.  This  indicates  hydroquinone  or  adurol. 

It  is  necessary  to  confirm  each  developer  by  the  following  characters 
and  tests.  They  are  given  rather  fully  because  it  'is'  only  by  a careful 
study  of  all  its  properties  that  a simple  developer  can  be  separated 
from  a complex  mixture. 

Developers  Yielding  No  Quinone. 

To  the  neutral  or  alkaline  solution  add  some  dilute  hydrochlorii 
acid  a crystalline  precipitate  (a)  insoluble  in  excess  of  hydrochlori' 
acid  indicates  eikonogen  (insoluble  acid). 

To  a I per  cent,  solution  j of  the  developer  in  water  acidified  wit'h 
hydrochloric  acid  add  6 per  cent,  of  sodium  chloride. 

A I per  cent,  solution  treated  as  above  gives  no  crystalline  precipi- 
tate. The  developer  in  solution  may  be  diamidophenol,  methylortho- 
amidophenol,  pyrocatechin,  or  pyrogallol.  N.B. — Diamidophenol,  hydro- 
chlorides are  precipitated  in  fine  crystals  on  nearly  saturating  witic 
sodium  chloride,  or  in  presence  of  excess  of  concentrated  hydrochlori- 
acid. 


37 


Separation  of  Complex  Developers. 

Developers  suspected  to  contain  two  or  more  simple  developers  may 
be  separated  to  a certain  extent  by  the  following  system : — When  a 
single  developer  has  been  isolated  and  fully  separated,  the  addition  of 
a little  sodium  peroxide  to  the  residual  liquid  will  tell  whether  there 
is  another  developer  present  in  quantity  ^or  not.  A considerable  darken- 
ing or  coloration  will  occur  if  there  is  a developer  present. 

If  the  developer  occurs  as  a solution  it  will  be  found  a safe  plan  to 
concentrate  an  acidified  portion  on  the  water-bath  before  proceeding 
to  separate  the  mixture.  When  a crystalline  precipitate  has  been  found 
in  any  stage  of  separation  it  must  be  all  removed. as  far  as  possible 
before  proceeding  to  the  next  step. 

If  a solid,  a somewhat  concentrated  solution  should  be  made  with 
the  aid  of  a little  acid  or  alkali,  if  necessary. 

Step  I. — To  the  neutral  or  slightly  alkaline,  somewhat  concentrated 
solution  add  some  hydrochloric  acid,  drop  by  drop,  stirring,  cooling, 
and  observing  carefully.  This  separates  as  a^  precipitate,  (a)  The 
free  acid  of  eikonogen  (insoluble  in  excess)  ; (b)  -the  free  acid,  glycin. 

Step  2. — To  a fresh  portion  of  the  original  somewhat  concentrated 
solution  (if  no  precipitate  in  step  i)  or  the  neutralized  filtrate  from 
step  I (if  there  was  a precipitate)  add  sodium  carbonate  solution,  drop 
by  drop.  A crystalline  precipitate,  insoluble  in  excess,  but  soluble  in 
caustic  soda,  indicates  paramidophenol. 

Step  3. — If  no  precipitate  to  the  acidified  solution  or  filtrate  from 
Step  I add  6 to  7 per  cent,  of  sodium  chloride.  This  separates  in  fine 
needles  the  free  acid  of  diogen. 

Step  4. — Shake  out  the  acid  solution  or  filtrate  from  Step  3 repeatedly 
with  ether,  adding  a little  chloroform  to  remove  the  ether  in  solution. 
The  ether  removes  (a)  hydroquinone,  (b)  adurol,  (c)  pyrogallol,  and 
(d)  pyrocatechin. 

Step  5. — If  no  residue,  take  a fresh  portion  of  the  original  liquid  or 
aqueous  liquid  from  Step  4;  acidify,  if  necessary,  with  hydrochloric 
acid,  and  evaporate  to  dryness  on  the  water-bath.  The  residue  consists 
of  the  developer,  together  with  some  chloride  and  sulphate,  which  do 
not  interfere  with  examination  by  color  reactions.  The  residue  may 
contain  (a)  amidol,  (b)  metol,  (c)  methylorthoamidophenol. 

Paramidophenol-hydro'chloride 

GH,OHNH.HCl 

I 

_/\_ 

ohJ  |_NH=HC1 

\/ 

I 

Comes  in  the  form  of  white  crystals  or  plates. 

Heated  on  platinum  foil  it  chars  without  fusing  and  emits  an  ex- 
tremely sharp  odor  of  phenol.  The  free  base  melts  at  154°  C.  with 
decomposition. 

Readily  soluble  in  cold  water  ard  in  alcohol,  insoluble  in  ether  and 
chloroform.  The  free  base  is  s(  luble  in  caustic  alkalies  and  to-  the 
extent  of  about  i part  in  90  parts  of  water. 

On  adding  alkaline  sulphites  and  carbonates  to  a solution  of  para- 
midophenol hydrochloride,  a mass  of  minute  glistening  crystals  is 
precipitated  (the  free  base).  On  further  adding  the  alkaline  salts  in 
excess  the  base  redissolves  and  forms  sodium  paramidophenolate.  On 
adding  a solution  of  potassium  hydroxide  to  a concentrated  solution 
of  paramidophenol  hydrochloride,  the  crystalline  base  is  precipitated 
as  above,  but  dissolves  in  excess  of  potassium  hydroxide  with  a deep 


38 


violet  coloration.  This  violet  coloration  is  an  alkaline  solution  of  the 
black  insoluble  oxidation  product  of  the  base.  On  adding  a little 
.alcohol  they  dissolve  with  a deep  violet  coloration. 

Is  precipitated  from  aqueous  solutions  by  concentrated  hydrochloric 
acid. 

If  a solution  of  paramidophenol  hydrochloride  be  acidulated  (hydro- 
chloric or  sulphuric  acid),  and  some  nitrite  solution  added  till  the 
smell  of  nitrous  acid  is  recognized,  a diazo  compound  is  formed  ih  the 
solution  which,  with  Andresen’s  a-naphthol-disulphonic  acid,  gives,  in 
caustic  alkaline  solutions,  a ponceau  red  dye. 

If  a solution  of  chlorinated  lime  is  added  to  a paramidophenol 
hydrochlorine  solution  acidulated  with  hydrochloric  acid  gives  at  first 
a violet  coloration.  On  adding  more  it  produces  a precipitate  of 
yellowish-white  flakes  or  flocks  of  chloramide  quinone  separate  out. 
(N.B. : — Not  given  by  a mere  tr^ce;  it  requires  a fair  amount  to  give 
the  reaction  well.) 

Ferrous  sulphate  gives  no  coloration;  ferric  chloride  gives  a fine 
violet  coloration,  becoming  red.  (N.B. ; — Not  given  by  a trace,  espe- 
cially if  the  ferric  chloride  is  in  excess.  Solution  rhust  be  moderately 
strong  to  show  the  reaction  well.  This  violet  color  is  then  permanent 
almost  to  the  boiling  point  of  water.) 

To  10  C.C.  of  raw  milk  add  about  o.os  grm.  of'  pararnidophenol 
hydrochloride  dissolved  in  a little  recently  boiled  and  cooled  distilled 
water,  and  then  add  i drop  of  hydrogen  peroxide  (20  volumes)  ; a 
pale  “cafe-au-lait”  color  is  produced.  Boiled  milk  gives  no  coloration 
under  similar  conditions. 


Metol 

Mono-methyl-paramidophenol-sulphate. 

2GH4  (OH)  NH2(CH3)  H2SO4 
Methyl-paramido-meta-cresol-sulphate. 
( GH3CH3NH.CH3)  2 ( H^S  O4) 

OH 


Buff  colored  acicular  crystals. 

Heated  in  a sublimation  tube,  it  swells  up  and  chars  without  fusion. 

It  emits  an  objectionable  nitrogenous  odor  (like  burning  bones)  and 
whitish  fumes.  It  gives  a mixture  of  whitish  and  tarry  sublimates. 
The  free  base  melting  at  87°  C.  The  metol  itself  melts  at  245  and 

257°  C. 

Very  soluble  in  hot  water,  insoluble  (or  very  sparingly  soluble)  in 
alcohol,  ether  and  chloroform.  The  free  base  is,  however,  soluble  in  , 
organic  'solvents. 

The  solution  boiled  with  some  concentrated  solution  of  caustic  soda 
gives  practically  no  coloration,  but  emits  a nauseous  odor  (resembling 
that  of  phenyl  isonitrile).  If  the  solution  is  made  alkaline  with  caustic 
soda,  the  base  is  liberated,  but  remains  in  solution,  unless  the  solution 
is  very  strong.  On  agitating  with  ether  (the  ether  does  not  change 
the  oxidation  coloring  matter),  and  evaporating  the  ether  on  a watch 
glass,  the  base  remains  as  oily  drops,  which  soon  set  to  a mass  of 
interlacing  aci-'-'ilaf  or  rosette  shaped  crystals. 


39 


By  adding  some  caustic  soda  to  Its  aqueous  solution  and  then  drop- 
ping in  some  dilute  sulphuric  acid,  while  immersed  in  ice  cold  water, 
there  is  precipitated  a mass  of  extremely  line  felt-like  needles.  Note : — - 
This  is  a nitroso  derivative  of  metol.  The  metol  solution  must' not  be 
too  dilute,  and  the  precipitate  only  appears  after  standing  a few" 
minutes  cooling  and  shaking. 

Solution  of  chlorinated  lime  gives  no  precipitate,  but  the  solution 
slowly  becomes  a fine  purple-violet  in  color  (distinction  from  para- 
phenylenediamine) . 

Ferrous  sulphate  gives  no  coloration.  -Very  dilute  ferric  chloride 
gives  very  slowly  a violet  coloration,  in  excess  it  gives  a deep  brown 
(quinone)  on  warming.  (Distinction  from  paraphenylenediamine). 

The  fact  that  metql  yields  a quinone  shows  that  it  is  a derivative  of 
phenol,  and  not  of  cresof  as  stated  by  some  authorities. 

10  c.  c.  of  raw  milk  treated  with  0.05  grams  of  metol  and  adding 
recently  boiled  and  cooled  water  (distilled)  and  further  adding  one 
drop  hydrogen  peroxide  (20  volumes)  gives  a dark  “cafe-au-laif' 
coloration.  Boiled  milk  gives  no  coloration. 


Amidol 

Diamidophenol-hydrochloride 
CcHUfOH)  (NH.)==HC1 
OH 
I 

NH.H  Cl 


NH^HQ 

A crj’Stalline  colorless  needle,  usually  resembling  powdered  mag- 
iiesium. 

Heated  it  chars  without  fusion,  with  a nitrogenous  odor  combined 
with  the  sharp  odor  of  the  hydrochloric  acid.  It  gives  a grey  and 
black  sublimate. 

Very  soluble  in  cold  water,  the  solution  soon  becoming  discolored,  and 
forming  a black  insoluble  powder.  The  acqueous  solution  hks  a 
characteristic  acid  reaction. 

On  adding  a few  drops  of  concentrated  solution  of  sodium  hydrox- 
ide to  the  solution  contained  in  a white  porcelain  basin,  it  becomes 
rapidly  a deep  reddish-brown  in  color.  Sodium  carbonate  added  to  a 
dilute  acqueous  solution,  produces  a fine  blue  coloration  (distinction 
triamidophenal).  The  blue  becomes  red  and  vice-v£rsa.,  according  to 
the  dilution,  etc. 

Ferric  chloride  gives  an  intense  blood-red  color,  becoming  violet-red 
on  dilution  with  a large  quantity  of  water.  Ferrous  sulphate  gives  no 
coloration. 

Ortol 

Methyl-ortho-amidophenol-sulphate  -f-  Hydroquinonc 
(A  molecular  mixture). 

GH,(OH)..  -f  CcH,(OH)  (NIH)  (CH5)2HjS04 
OH  OH 

A_  ■ NH«  H.SO4 

J L + _1L  2 

Y 

OH 


40 


In  fine  flat  rhombic  crystals  or  prisms  becoming  discolored  on  ex- 
posure to  light  and  the  air. 

Heated  it  chars  without  fusion,  giving  a tarry  sublimate  and  an 
offensive  nitrogenous  odor  (like  stale  cabbage).  The  latter  odor  is 
partly  due  to  decomposition  of  the  sulphate..  The  tarry  sublimate 
ultimately  crystallizes  in  radiating  clusters.  The  free  base  melts  at 
8o°  C.  with  decomposition. 

Very  soluble  in  water,  particularly  soluble  in  alcohol  and  ether 
(hydroquinone  dissolves). 

On  adding  a few  dropS  df  a concentrated  solution  of  caustic  soda, 
the  solution  becomes  very  slowly  pale-brownish.'  On  heating  the  solu- 
tion it  emits  an  odor  of  burning  proterid.  On  adding  caustic  soda  the 
free  base  remains  in  solution  unless  the  solution  is  very  strong.  It 
may  be  “salted  out’’  of  solution.  Note: — The. oxidation  coloring  matter 
is  soluble  in  ether  (compare  with  metol). 

Ferrous  sulphate  gives  no  coloration;  ferric  chloride  gives  a deep 
red  color. 

To  lo  c.c.  of  raw  milk  add  about  i c.c.  of  a-  t per  cent,  solution  of 
ortol,  dissolved  in  recently  boiled  and  cooled  distilled  water,  and  then 
add  I drop  of  hydrogen  peroxide  (20  volumes),  gives  a deep  brick-red 
coloration  (Saul’s  test  for  raw  milk).  Boiled  milk  gives  no  coloration.- 

HYDROQUINONE ; PARA-DI-OXY-BENZOL 
CeH,(OH), 


In  long  prisms  or  hexagonal  needles  of  the  ortho-rhombic  system. 
Yellowish-white  in  color  with  no  taste  or  odor. 

Melts  at  169°  C.  to  a colorless  liquid  and  sublimes  in  white  fumes, 
leaving  no  residue.  Boiling  at  285°  C. 

Soluble  in  i in  ro  of  water  at  15°  C. ; more  readily  in  hot  water. 
Readily  soluble  in  alcohol  ether  and  benzene.  Insoluble  in  chloro- 
form. 

Lead  acetate  gives  no  pr.ecioitate  in  moderately  dilute  solution  (dis- 
tinction from  pyrogallol  and  pyrocatechin,  a mere  trace  of  which 
gives  a precipitate  with  lead  acetate). 

0.05  grms.  dissolved  in  about  7 C.C.  of  water  and  two  drops  of 
copper  acetate  added  gives  a deep  yellow  coloration. 

Nitric  acid  transforms  it  into  oxalic  acid. 

Dissolves  without  alteration  in  normal  and  acid  sulphite  solution 
from  which  it  deposits  as  yellow  crystals  containing  sulphurous  acid. 

Not  separated  from  alkaline  solution  by  agitating  with  ether;  it  is, 
however,  removed  by  acidifying. 

Ferric  chloride  at  first  gives  a green  coloration  (green  compound 
of  hydroquinone  and  quinone).  The  green  solution  becomes  rapidly 
reddish-brown  (quinone),  and  ultimately  gives  a brownish-yellow  crys- 
talline precipitate  of  quinone  dissolving  on  adding  a few  drops  of 
alcohol.  Ferrous  sulphate  gives  no  coloration. 

Add  I part  of  concentrated  sulphuric  acid  an^d  i part  potassium 
bichromate  in  20  parts  of  water,  by  adding  se-verat  drops  of  this  solu- 
tion to  a hydroquinone  solution  on  being  heated,  a pungent  odor  of 
quinone  is  obtained. 


41 


Adurol 

Mono-brom-hydroquinone  CeHaCOH)  Br. 
Mono-chlor-liydroquinone  GHsCOH) Cl. 


OH 


I OH  Br.orCl. 


Mono-brom-hydroquinone : — Leaflets. 

Mono-chlor-hydroquinone : — White  crystalline  powder. 

Mono-brom-hydroquinone  melts  at  ili°  C. 

Mono-chlor-hydroquinone  melts  at  io6°  C. 

(Distinction  from  hydroquinohe).  Both  behave  similar  to  hydro- 
quinone  on  heating. 

The  brom  and  chlor  products  are  readily  soluble  in  water.  Very 
soluble  in  alcohol  and  ether;  slightly  soluble  in  chloroform. 

Ferric  chloride  gives  a reaction  similar  to  that  given  by  hydroquinone. 
b.os  mgr.  dissolved  in  about  7 C.C.  of  water  and  two  drops  of  copper 
acetate  added  gives  a very  pale-green  coloration  (distinction  from 
hydroquinone) . 

Lead  acetate  reaction  is  the  same  as  that  given  by  hydroquinone. 

Ultimate  organic  analysis  (careful  charring  in  presence  of  a small 
piece  of  sodium,  acidifying  with  nitric  acid,  etc.)  shows  the  presence  of 
chlorine  or  bromine.  This  , coupled  with  the  fact  that  chloride  or 
bromide  is  absent  in  the  original  substance,  and  the  substance  wholly 
sublimes,  proves  it  to  be  a haloid  derivative  of  hydroquinone. 


In  very  light  or  fleecy  white  crystalline  masses  or  dense  needle 
shaped  crystals. 

Melts  at  132°  C.  to  a colorless  liquid,  which  boils  at  210“  C.  with 
white  fumes,  and  at  250°  C.  it  splits  into  meta  gallic  acid  and  .water, 
leaving  practically  no  residue. 

Extremely  soluble  in  2'A  parts  cold  water,  i part  alcohol  and  1% 
parts  of  ether,  with  difficulty  in  benzene,  chloroform  and  carbon 
disulphide. 

The  acqueous  solution  turns'  brown,  then  black  in  the  air,  depositing 
black  flocks  and  evolving  carbon  dioxide.  Acids  prevent  this  decom- 
position. 

in  the  presence  of  alkalies,  pyrogallol  rapidly  absorbs  oxygen,  the 
solution  becoming  yellowish,  then  brown  and  lastly  brown-black, 
especially  on  exposure,  and  the  addition  of  caustic  soda  increases 
the  reaction.  . 

On  adding  lime  water,  the  liquid  assumes  a line  red  tint  which 

turns  brown.  , , , . • 

Warmed  with  nitric  acid  in  the  presence  of  sulphuric  acid,  it  gives 
a yellow  solution,  rapidly  giving  on  dilution  a yellow  crystalline  pre- 
cipitate (picric  acid.) 


Pyrogallol;  Trioxybenzol 


CoH3(OH)3 

OH 


\ 


42 


Pyrogallol  is  separated  by  ether  from  sulphite  solutions,  but  not  from 
sulphite  and  potash  solutions. 

The  addition  of  i drop  of  Liquor  Calcis  Sacch  to  the  solution  pro- 
duces an  intense  purple  coloration,  becoming  gradually  brown  by 
oxidization. 

Potassium  permanganate  decomposes  it,  liberating  carbon  dioxide  with 
effervescence  in  concentrated  solution.  The  potassium  permanganate 
is  discolored. 

Heated  with  potassium  permanganate  and  sulphuric  acid,  the  solu- 
tion cooled  and  shaken  out  with  ether,  gives,  on  evaporation  of  the 
ether,  a residue  of  garhet-red  crystals  (purpurogalic  acid).  These 
crystals  give  a transient  blue  color  with  alkalies. 

Heated  with  anhydrous  phthalic  acid  and  hot  sulphuric  acid,  yields 
a staple  green  color  or  dye  (coerulein). 

The  solution  in  recently  boiled  and  cooled  distilled  water  of  a 
washed  crystal  of  ferrous  sulphate,  added  to  a very  dilute  solution 
of  pyrogallol  in  boiled  distilled  water,  produces  no  coloration  at  first, 
but  the  solution  becomes  gradually  a fine  indigo  blue.  Ferric  chloride 
gives  a brownish-red  coloration,  gradually  deepening  and  becoming 
dark  brown  on  adding  sodium  carbonate. 


In  tabular  crystals  or  rhombic  plates  white  or  slightly  violet  colored. 
Is  sold  in  commerce  with  potassium  metabisulphite  which  acts  as  a 
preservative  as  eikonogen  oxidizes  very  readily  in  the  air. 

The  free  acid,  dried  and  heated  in  a sublimation  tube,  chars  without 
fusion,  with  a nitrogenous  odor  and  also  an  odor  of  sulphur  dioxide. 
It  gives  a tarry  sublimate.  When  heated  to  iio°  C.,  it  loses  2)4 
molecules  of  water  of  crystallization. 

The  solubility  in,  cold  water  is  about  2 per  cent.,  more  soluble  in 
boiling  water,  insoluble  in  alcohol,  ether  and  chloroform.  The  free 
acid  is  soluble  in  boiling  water,  but  insoluble  in  organic  solvents. 

Acids  precipitate  the  frbe  base  in  fine  white  needles  from  an  aqueous 
solution  of  eikonogen,' this  precipitate  is  insoluble  in  excess  of  hydro- 
chloric acid  (distinction  from  glycine  and  diphenyl) 

Alkaline  solutions  have  a golden  yellow  color. 

Ferrous  sulphate  (or  very  dilute  ferric  chloride)  gives  a fine  violet 
color,  becoming  olive-green  and  finally  reddish-yellow.  Ferric  chloride 
gives  a reddish-yellow  coloration.  Note The  presence  of  a small 
quantity  of  sulphite  does  not  interfere. 

On  adding  a 25  per  cent,  solution  of  a potassium  salt  to  a saturated 
solution  a glittering  crystalline  precipitate  of  potassium  amido-B- 
naphthol-mono-sulphonate  is  throwii  down.  It  is  soluble  in  boiling 
water.  A 15  per  cent,  sodium  salt  gives  no  crystalline  precipitate. 
Note: — A 15  per  cent,  solution  of  a potassium  salt  will  give  a precipi- 
tate, but  the  reaction  is  not  so  evident,  especially  when  the  solution  is 
colored  by  exposure. 

10  c.c.  of  raw  m.ilk  treated  with  0.05  gms.  of  eikonogen  dissolved  in 
recently  boiled  and  cooled  distilled  water,  and  then  add  i drop  of  (20 
volumes)  of  hydrogen  peroxide,  gives  no  immediate  coloration,  but 
the  solution  becomes  slowly  salmon  colored. 


Eikonogen 

Sodium-a-amido-B-naphthol-monosulphonic  acid 
GoH=(OH)  (NHO  (SONa)2H.O 


43 


Pyrocatechin ; Brenzcatechin ; Kachin 
C,H4(0H)2 
OH  OH 


White  broad  flakes  (from  benzol),  prismatic  needles  (from  water). 

Heated  it  melts  at  104°  C.  to  a colorless  liquid,  which  sublimes  in 
sharp  aromatic  vapors,  leaving  practically  no  residue. 

Very  soluble  in  water,  alcohol,  benzol  and  ether;  sparingly  soluble 
in  chloroform. 

Dilute  acids  do  not  affect  it;  gives  practically  no  coloration  when 
rnade  alkaline  with  sodium  carbonate  solution,  even  when  boiled  (dis- 
tinction from  pyrogallol). 

Can  not  be  separated  from  an  aqueous  solution  by  shaking  with 
ether  in  the  presence  of  caustic  alkalies.  After  acidulation  of  the 
solution  is.  taken  up  by  the  ether. 

Solution  of  lead  acetate  causes  a white  precipitate  with  aqueous  solu- 
tion of  pyrocatechin. 

Liquor  Calcis  Sacch  gives  no  coloration  (distinction  from  pyrogallol). 

Ferric  chloride  gives  an  emerald-green  coloration.  Ferrous  sulphate 
gives  a blue  coloration  exactly  similar  to  that  given  with  pyrogallol. 


Micaceous  plates. 

Heated  it  melts  and  decomposes  in  whitish  fumes  with  a disagreeable 
nitrogenous  odor.  The  charred  mass  liquifies  and  swells  up  in  the  .sub- 
limation tube,  and  gives  a crystalline  sublimate. 

Dissolves  with  difficulty  in  water  (about  i in  30),  more  soluble  in 
boiling  water  (the  solution  not  being  discolored),  crystallizing  out  on 
cooling  in  very  glistening  crystals.  Practically  insoluble  in  alcohol. 
Insoluble  in  ether,  chloroform  and  acetic  acid.  The  aqueous  solution 
is  strong!)^  acid. 

On  adding  a quantity  in  excess  of  its  solubility  to  a little  water,  and 
then  adding  two  or  three  drops  oS  hydrochloric  acid,  the  excess  will 
dissolve  readily.  Then  on  carefully  dropping  sodium  hydroxide  solu- 
tion until  neutral,  it  is  precipitated  in  glistening  micaceous  crystals. 
On  adding  a few  drops  of  alkali  in  excess  it  redissolves.  (Note:  This 
is  due  to  the  fact  that  glycine,  being  an  amido  acid,  is  soluble  both  in 
acids  and  alkalies  to  form  salts.) 

An  acidulated  (with  dilute  sulphuric  acid)  glycine  solution  gives 
off  the  characteristic  quinone  odor  with  effervescence,  on  oxidation 
with  potassium  bichromate,  with  an  evolution  of  carbon  dioxide  (test 
with  lime  water). 

Solution  of  chlorinated  lime  added  to  an  acidulated  solution  gives 
no  crystalline  precipitate. 

Ferrous  sulphate  gives  no  coloration ; ferric  chloride  has  no  action 
except  a slight  decoloration  due  to  reduction. 

To  ten  mils,  of  raw  milk  add  about  0.05  grams  of  glycine  dissolved 
in  recently  boiled  and  cooled  distilled  water,  then  add  one  drop  hydro- 
gen peroxide  (20  volumes).  No  immediate  coloration  is  produced. 
After  a short  time  it  gradually  becomes  a pinkish  tint.  Boiled  milk 
gives  .no  coloration. 


Glycine;  Para-oxy-phenyl-amido-acetic  acid 


i,  iftc  j jt  y-ynu  n vc~Li’irtiuu~uL 

GH^fOH)  (NH=)  (CH.COOH) 


,/\_NH 


OH 


C O O H 


44 


DIOGEN. 


Sodium-a-amido-B-naphihol-disulphonic  acid. 

OOHHOH)  (NH2)  (S03Na)2 

A yellowish  powder  combined  with  potassium  metabisulphite  as 
a preservative. 

The  free  acid  chars  slowly  without  fusion,  emitting  a nitrogenous 
odor,  combined  with  the  odor  of  sulphur  dioxide.  It  gives  a yellowish- 
white  crystalline  sublimate  (free  sulphur). 

It  is  moderately  soluble  in  cold  water,  easily  in  hot  water,  emitting 
an  odor  of  sulphur  dioxide  (potassium  metabisulphite),  insoluble  in 
organic  solvents. 

The  free  acid  is  soluble  in  cold  water  (compare  the  acid  of  eikono- 
gen)  but  is  readily  “salted  out”  by  about  6 to  7 per  cent,  of  sodium 
chloride.  The  free  acid  dissolves  in  alkalies  with  a pale  reddish  color. 
The  free  acid  of  eikonogen,  under  similar  circumstances,  dissolves  with 
a deep  red-brown  coloration. 

Ferrous  sulphate  gives  a bluish-violet  coloration,  becoming  green 
and  finally  reddish-yellow.  Ferric  chloric  gives  a reddish-yellow  colora- 
tion. 

A 1 0 per  cent  solution  of  a potassium  salt  added  to  a saturated 
solution  of  diogen  gives  a crystalline  precipitate  (distinction  from 
eikonogen) . 

10  c.c.  of  raw  milk  treated  with  0.05  grams  of  dogen  dissolved 
in  a little  recently  boiled  and  cooled  distilled  water,  and  then  add  one 
drop  of  hydrogen  peroxide  (20  volumes)  ; gives  no  coloration  for  some- 
time. At  the  end  of  five  minutes  there  is  only  an  indefinable  greyish 
discoloration. 

PARAMINE. 

Paraphen^lenediamme-h})drochloride 
C6H^NH2)2  2 HCl 

Triclinic  tablets,  the  free  base  crystallizes  from  ether  in  tablets. 
From  water  monoclinic  crystals  are  obtained  which  are  converted  in 
the  water  into  rhombic  plates. 

Decomposes  without  melting.  The  free  base  melts  at  1 40  deg.  C. 
to  a clear  brownish-yellow  liquid,  which  boils  and  rapidly  sublimes  in 
whitish  fumes,  leaving  a trace  of  glassy  charred  residue. 

Easily  soluble  in  water  to  a pale  brownish  solution  (note  the  scaly 
appearance  of  the  crystals  as  the  dissolve.  Readily  soluble  in  alcohol 
and  chloroform.  Sparingly  soluble  in  ether. 

45 


On  dissolving  in  a little  alcohol  and  adding  one  or  two  drops  of 
hydrochloric  acid  a mass  of  small  needle  shaped  crystals  (the  hydro- 
chloride) slowly  separates.  On  dissolving  in  a little  ether  and  adding 
one  drop  of  hydrochloric  acid  there  is  an  immediate  white  sandy  precipi- 
tate. The  precipitated  hydrochloride  is  readily  soluble  in  water. 

Sodium  hydroxide  gives  no  coloration  even  on  boiling,  and  omits 
no  nauseous  odor. 

A solution  of  chlorinated  lime  added  to  an  acidulated  solution 
of  a mere  trace  of  paraphenylene  diamine-hydrochloride,  produces  a 
precipitate  of  quinone-dichloro-dimide,  which  separates  in  white  flakes. 

The  nitroso  reaction  is  negative. 

Ferric  chloride  gives  a violet  coloration,  becoming  rapidly 
brownish-red  (quinone).  Also  produced  by  chlorine,  etc.  Ferrous 
sulphate  gives  no  coloration  at  first,  but  the  solution  becomes  slowly 
bluish. 

10  c.c.  of  raw  milk  treated  with  0.01  grams  of  paraphenylenedi- 
amine  hydrochloride  dissolved  in  recently  boiled  and  cooled  distilled 
water,  and  then  add  1 drop  (20  volumes)  of  hydrogen  peroxide,  gives 
an  immediate  deep  bluish  color,  gradually  becoming  bluish-black.  Boiled 
milk  gives  no  immediate  coloration.  After  the  lapse  of  a minute  the 
mixture  becomes  slate  colored,  gradually  deepening. 

The  diazo  compound  of  paraphenylene-diamine-hydrochloride 
gives  with  Andresen’s  a-naphthol-disulphonic  acid  a red-violet  color 
(compare  with  para-midophenol) . The  shade  of  this  dye  is  best  de- 
termined by  pouring  some  of  the  solution  on  filter  paper,  and  dropping 
dilute  acetic  acid  on  the  place. 

DIAMINE. 

Diamido-resorcin-hydrochloride 

C6H2(0H)2(NH^)22  H Cl 

Tabular  crystals  or  rhombic  tables. 

Decomposes  by  heat  without  fusion,  with  a nitrogenous  odor. 

Easily  soluble  in  water,  almost  insoluble  in  alcohol  and  ether; 
insoluble  in  chloroform. 

A few  drops  of  a concentrated  solution  of  sodium  hydroxide  added 
to  the  solution  contained  in  a white  porcelian  basin  gives  an  intense  blue 
color  (distinction  from  di  and  tri-amidophenol) . Note — This  test  may 
also  be  applied  by  suspending  the  hydrochloride  in  chloroform,  adding 
a little  aqueous  sodium  hydroxide,  followed  by  a large  quantity  of  water. 

A fine  blue  coloration  is  produced. 

46 


Aqueous  sulphite  solution  gives  with  potassium  carbonate  a yel- 
lowish-brown color. 

Very  dilute  ferric  chloride  gives  an  intense  violet  color,  and  de- 
stroyed until  the  solution  is  boiled  for  some  time. 

REDUCIN. 

T riamidophenol-hydrochloride 

C«H2(OH)  (NH2)3  3HC1 

In  very  fine  needles. 

Chars  without  fusion  with  a powerful  nitrogenous  odor,  combined 
with  that  of  hydrochloric  acid. 

Easily  soluble  in  water,  almost  insoluble  in  alcohol  and  ether, 
insoluble  in  chloroform. 

Alkaline  sulphite  make  the  solution  yellowish.  By  adding  potash 
the  color  becomes  green.  On  adding  a few  drops  of  concentrated  solu- 
tion of  caustic  soda  to  the  solution  contained  in  a white  porcelian  basin 
it  becomes  rapidly  a deep  reddish-brown  in  color.  The  colors  are  very 
distinct  if  filter  paper  be  saturated  with  the  solution  and  exposed  to 
the  air. 

Sodium  carbonate  added  to  a dilute  aqueous  solution  produces  a 
mouldy  green  coloration,  becoming  brown  on  adding  caustic  soda. 

One  drop  of  ferric  chloride  gives  a very  deep  blue  coloration. 
Note — Due  to  the  formation  of  the  blue  crystalline  compound  amido- 
diamidophenol-hydrochloride. 

DIPHENYL. 

Diamido-ox^-diphenyl-hpdrochloride 
02H6(OH)  (NH2)2  2 HCl 

Long  silky  looking  needles. 

Heated  it  chars  without  fusion;  with  a nitrogenous  odor,  but  no 
odor  of  sulphur  dioxide.  The  free  base  melts  at  148  deg.  C. 

Readily  soluble  in  hot  water,  almost  insoluble  in  cold  water,  solu- 
ble alkaline  solutions  also  in  excess  of  hydrochloric  acid,  and  in  alcohol 
and  glacial  acetic  acid,  with  difficulty  in  benzene. 

Ferric  chloride  gives  a deep  red  coloration. 

Copper  acetate  gives  a green  coloration. 

The  diazo  compound  of  diphenyl  gives  with  Andresen’s  a-naphthol- 
disulphonic  acid  a poncean  red  dye  (compare  with  paramidophenol) . 

10  c.c.  of  raw  milk  treated  with  0.01  grams  of  diphenyl  dis- 
solved in  recently  boiled  and  cooled  distilled  water  and  then  add  1 drop 
of  hydrogen  peroxide  (20  volumes),  gives  practically  no  change  ia 
coloration. 


47 


Wein.  American  Annual  of  Photo,  page  292,  1918. 

PHOTOGRAPHIC  DEVELOPERS 


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NAME  AND  SUBJECT  INDEX 


AEG  A Co.  Page 

p-phenylenediamine 6 

amido-p-phenylenediamine  — oxy  - p - phenylenediamine  — 

amido-p-toluylenediamine 7 

diamido-naphthol  disulphonic  acid 15 

p-oxy-phenylglycinamide 23 

metol  25 

oxy-phenyl  methyl  glycine  — methyl  p-amidophenol 28 

Anresen 

p-phenylenediamine  — amidonaphthol  monosulphonic  acid 

— dioxy  naphthol  monosulphonic  acid 1 

a-amido-J3-sulphonic  acid 8 

dimethyl-p-phenylenediamine 4 

dimethyl-p-amidophenol 4 

Baum 

o-bromophenol  — o-chlorophenol  — pyrocatechin  — a- 

phenol  disulphonate 7 

Bayer 

o-nitrophenol 16 

pyrogallol 17 

p-amidosaligenin  — p-nitrophenol  — o-nitrophenol 18 

chlor-methyl-p-nitrophenol 19 

m-amido-o-oxy  benzyl  sulphonic  acid 21 

Buisson 

p-amidophenol  — diamidophenol  — hydroquinone  — 

pyrocatechin  13 

Brocket 

p-amidophenol  — p-phenylenediamine 28 

Cassella 

acetyl  oxyazobenzene  — oxy  diamido  diphenyl 14 

Cazeneuve 

pyrogallol 6 

Claus 

dinitrophenol 25 

51 


Page 


Cramer 

hydroquinone  — pyrogallol 15 

Darmstadter 

hydroquinone 14 

p-amidophenol  16 

Eichengrun  and  Demeler 

chlor  methyl-p-nitrophenol 20 

Fischer 

p-phenylenediamine  — p-amidophenol 26 

Gatterman 

o-nitrophenol  — p-nitrophenol  — phenyl  hydrazine  hyro- 

chloride 12 

Grandmougin 

p-hydroxyazobenzene 25 

Harger 

hydroquinone  — metol 31 

Harrison  and  Bottomly 

Pinacyanol  34 

Orthochrome  T 35 

Hauff 

metol  3 

o-p-diamidophenol  — o-p-diamido-o-cresol  — o-p-diamido- 
m-cresol  — methyl-o-amidophenol  — hydroquinone  — 

pyrocatechin  . 10 

p-phenylenediamine  — hydroquinone  — pyrocatechine  — 

p-toluylenediamine  — p-xylenediamine 13 

p-phenylenediamine  — p-toluylenediamine 14 

hydroquinone  — hydrotoluquinone  — pyrocatechin  — 

pyrogallol  — hydronaphthoquinone 15 

Hoffman 

naphthol  green  32 

Jacobsen 

Quinoline  red  — Quinoline  yellow 32 

Jansen 

p-phenylenediamine  28 

Kempf 

hydroquinone 16 

Leaper 

Quinoline  blue  — Cyanin  — Isokol.  34 

Lembach  and  Schleicher 

o-quinoline  — p-quinoline 13 


52 


Page 


Levinstein  and  Pollak 

a-amido-a-nitro-a-sulphonic  acid  — a-a-naphthylamine-a- 

sulphonic  acid 15 

Lumiere 

oxy-quinoline  — oxy-tolu  quinoline 4 

methyl  amido  p-oxybenzene  sulphate 22 

Lumiere  and  Jougla 

adurol 30 

Lumiere  and  Seyewetz 

constitution  of  developers 5 

p-tolyl  B-hydroxyl  amine  9 

p-amidophenol 8 

hydroquinone 16 

trioxy  methylene  and  pyrogallol 22 

benz  amido  semicarbide  — benz  amido  semicarbazide  — 

benzamide  hydrazine 22 

p-phenylenediamine  23 

methyl  hydroquinone  30 

Luttke  and  Arndt 

p-amidophenol  hydrochloride  23 

Meister-Lucius  and  Pruning 

dihydroxy  naphthol 30 

p-amidophenol  sulphate 16 

sodium  glycocol  21 

Meldola 

Eikonogen  2 

Merck 

hydroquinone  — metol  29 

Meyer 

Quinoline  yellow 35 

Miethe  and  Traube 

Pinacyanol 34 

Monnet  and  Cartier 

p-nitrophenol  — p-amidophenol  — o-nitrotoluene  p-sulphonic 

acid  — p-toluene  sulphonyl  chloride 9 

Noyes  and  Clement 

p-amidophenol 6 

Paul 

p-nitrophenol  — o-nitrophenol  — p-amidophenol  — p- 

amidophenol  sulphate  — metol  — p-hydroxyglycine . .10-15 
Pellizzari 

p-amidophenol  acetone  bisulphite  — metol 23 

Perkin 

pyrocatechin  — guaiacol 2 

Reverdin  and  de  la  Harpe 

dinitrophenol 4 


53 


Page 


Schwartz  and  Mercklin 

hydroxylamine  oxymethyl  sulphonate 1 

Stebbings 

amido-5-naphthol  a-sulphonic  acid  — dimethyl  p-pheny- 

lenediamine  * 1 

Sobering 

hydroquinone 8 

p-amidophenol  — benzyl  p-amidophenol 23 

9 

hydroquinone  — pyrocatechin  — pyrogallol 13 

Society  of  Chemical  Industry 

p-amidophenol 31 

Tafel 

hydroxylamine 22 


Tauber 

p-amidophenol  — p-azophenol  16 

Thorpe 

hydroquinone  — pyrogallol 26 

Ufer-Driebrodt  and  Rohler 

glycolates  30 

Vidal 

dinitrophenol 17 

p-amidophenol  — o-amidophenol 14 

p-phenylenediamine  25 

Weinberg 

Formyl  violet  33 

54 


Wein 


p-amidophenol  hydrochloride 36 

metol  37 

amidol  38 

ortol 39 

hydroquinone  40 

adurol 41 

pyrogallol  42 

Eikonogen 43 

pyrocatechin  44 

glycine 45 

Diogen  — Paramine 46 

Diamine 47 

Reducin  — Diphenyl 48 

table  of  developers 49-50 

WOLFFENSTEIN  AND  BoLTERS 

dinitrophenol  . 29 

Ziegler 

Tartrazine  33 


VOLUME  II. 


I 


The  following  pages  is  a complete  survey  of  all  the  chemical 
manipulations  involved  in  photography. 


Samuel  Wein. 


N 


58 


CHAPTER  I. 


DEVELOPING. 

The  term  “developer”  is  often  misunderstood,  some  are  inclined 
to  believe  that  it  applies  to  the  solution  itself.  Whereas,  the  fact  is 
that  it  only  applies  to  the  compound  or  agent  which  actually  reduces 
or  makes  visible  the  “latent  image”  or  exposed  silver  salt. 

The  composition  of  developing  solutions  varies  not  only  with  the 
compound  used,  but  even  with  the  individual  photographer. 

The  following  is  a review  of  the  developing  solutions  and  some  of 
its  characteristics,  this  by  no  means  is  complete.  For  detailed  informa- 
tion concerning  these  developers,  reference  should  be  had  to  such  per- 
iodicals as  are  referred  to  throughout  the  text. 


/ 


ADUROL. 

The  development  with  Adurol  is  preferred  to  Hydroquinone,  in 
view  of  the  fact  that  it  gives  much  softer  negatives  and  prints,  with 
plenty  of  density  and  good  detail.  Its  solution  is  not  so  readily  affected 
by  atmospheric  changes  as  it  is  with  Hydroquinone.  On  developing 
with  Adurol  the  high  lights  and  shadows  quickly  appear  and  the  half 
tones  are  built  up  little  by  little,  giving  a blue  black  image  which  is 
desirable  for  bromide  prints.  A typical  developing  solution  being; 


Water 7 ounces 

Adurol ounce 

Sodium  sulphite  ounces 

Potassium  carbonate 2Yl  ounces 


For  use  dilute  with  from  five  to  seven  times  its  volume  of  water. 


59 


amidol 

Amidol  is  one  of  the  fines^  developers,  giving  fine  detail  in  the 
shadows  and  free  from  fog. 

It  develops  in  the  presence  of  sodium  sulphite  only  and  in  fact 
the  neutral  salt  is  preferred  for  this.  In  alkaline  solution  it  rapidly 
oxidises  and  is  unfit  for  use  as  a developer  as  it  stains  the  negative 
yellowish. 

The  following  solution  is  recommended  as  giving  very  strong 
contrasts  and  being  suitable  for  bromide  prints: 


Amidol 24  grains 

Sodium  sulphite  80  grains 

Sodium  bisulphite  1 ounce 

Potassium  bromide  20  grains 

Water  10  ounces 


This  solution  will  keep  well  for  a long  time. 


EDINOL. 

Edinol  as  a developer  the  fine  qualities  of  Pyrogallol  with  those 
of  the  more  rapid  developers,  giving  great  density  or  softness,  according 
to  the  manner  in  which  it  is  used.  With  caustic  alkalies  very  soft 

gradations  may  be  obtained,  while  with  the  use  of  sodium  carbonate, 
the  tendancy  is  towards  strong  contrasts. 

The  following  solution  is  recommended  for  all  aronud  work: 


Edinol 9 grains 

Soodium  sulphite 18  grains 

Potassium  carbonate  90  grains 

Water  20  ounces 


Edinol  develops  free  from  fog  and  does  not  stain  or  affect  the 
skin  as  other  developers  do. 


60 


DIAMINE. 


The  developmemt  with  Diamine  is  very  much  the  same  as  with 
Amidol,  in  that  it  develops  in  the  presence  of  sodium  sulphite  only. 
A typical  formula  is: 

Sodium  sulphite  250  grains 

Diamine  85  grains 

Water  to  20  ounces 

This  solution  will  keep  well  in  amber  colored  bottles. 

DIPHENAL. 

This  developer  is  supplied  in  the  form  of  a brown  solution,  it  is 
used  much  the  same  as  Rodinal.  With  correctly  exposed  negatives  it 
is  dulated  with  from  15  to  20  parts  of  water.  For  over  exposed 
negatives,  it  is  diluted  with  from  8 to  1 0 parts  of  water.  For  under 
exposed  negatives  it  is  diluted  with  from  20  to  25  parts  of  water. 


DURATOL. 

Duratol  has  unusual  developing  strength,  is  soft  working  and  is 
recommended  for  snap  shots.  It  does  not  spoil  in  solution  so  readily  as 
other  developers  do. 

It  is  no  longer  obtainable  on  the  market. 

EIKONOGEN. 

Eikonogen  is  a soft  working  developer,  the  range  of  gradation 
in  tones  is  more  harmonious  than  is  possible  with  Pyrogallol.  It  gives 
blue  black  or  grey  prints. 

The  following  is  recommended  for  portrait  negatives: 

Eikonogen  52J/2  grains 

Sodium  sulphite 52*/2  grains 

Sodium  carbonate 52^  grains 

Potassium  bromide  2 grains 

Water  5 ounces 

For  softer  effects  add  up  to  an  equal  volume  of  water.  The 
image  appears  quickly  and  builds  up  in  density  quite  fast. 


61 


Eikonogen  is  widely  advocated  for  very  rapid  exposures,  for  which 
the  following  solution  is  suitable: 


Eikonogen  100  grains 

Sodium  sulphite  200  grains 

Sodium  carbonate 100  grains 

Potassium  bromide  5 grains 

Water  16  ounces 


, The  small  quantity  of  potassium  bromide  added  appears  to  in- 
crease the  density  of  the  negative,  if  the  negative  is  under  exposed  or  a 
soft  negative  is  desired,  it  is  better  omittd. 


GLYCIN. 

Glycin  is  a slow  working  developer  and  keeps  well  for  a long 
time  in  solution.  It  is  for  this  reason  that  it  is  suitable  for  tank  develop- 
ment. The  negatives  developed  with  it  are  perfectly  clear  and  free 
from  stain. 

Von  Hubl  recommends  the  following  Glycin  paste  consisting  of: 


Sodium  sulphite  2Yl  ounces 

Water  (boiling)  4 ounces 

When  dissolved  add: 

Glycin  1 ounce 

And  then  in  small  quantities: 

Potassium  carbonate 5 ounces 


This  forms  a thick  paste,  which  must  be  well  shaken  and  then 
diluted  with  water,  for  normal  exposures  dilute  1 ounce  of  the  paste 
with  1 2 to  15  ounces  of  water,  for  very  soft  results  dilute  with  30 
ounces  of  water. 

A single  Glycin  solution  is  made  up  from: 


Glycin 1 ounce 

Sodium  sulphite  2Yl  ounces 

Potassium  carbonate 5 ounces 

Water  to  30  ounces 


For  normal  exposure  dilute  with  an  equal  bulk  of  water. 


62 


METHYL  GLYCIN. 


A suitable  formula  which  must  be  diluted  with  an  equal  quantity 
of  water  before  used  is  the  following: 


Methyl  Glycin 350  grains 

Potassium  carbonate  175  ounces 

Sodium  sulphite  2 grains 

W ater  16  ounces 


A similar  solution  was  prepared  with  the  ordinary  Glycin  and 
comparative  results  proved  that  the  new  preparation  gave  good,  clean 
negatives  in  a much  shorter  time  than  the  older  developer.  As  regards 
and  Metol.  The  sensitiveness  of  the  developer  to  changes  of  tempera- 
speed  of  development  Dr,  Valenta  places  it  midway  between  Glycin 
ture,  appears  to  be  about  the  same  as  that  of  Glycin. 

The  action  of  potassium  bromide  appears  to  be  about  one-fourth 
of  that  of  Glycin. 


HYDRAMINE. 

This  developer  works  best  with  lithium  hydroxide,  the  following 
solution  is  recommended  by  Lumiere: 


Hydramine  ounce 

Sodium  sulphite  ounce 

Lithium  hydroxide  65  grains 

Water  50  ounces 


For  over  exposures  add  several  drops  of  a 10  per  cent,  solution 
of  potassium  bromide,  for  under  exposure  add  several  drops  of  a 1 
per  cent,  solution  of  lithium  hydroxide  solution. 

HYDROQUINONE. 

Hydroquinone  like  Pyrogallol  is  used  to  a great  extent.  It  is  a 
slow  working  contrasty  developer.  Hydroquinone  is  more  sensitive  to 
temperatures  than  other  developers,  in  fact  by  increasing  the  temp- 
erature of  the  solution  it  will  give  excessive  contrasts  and  fogs  the 
negative.  Should  the  temperature  be  lowered  it  is  apt  to  crystallize 
out.  The  ideal  temperature  is  between  65  to  70  deg.  F, 


63 


Sodium  hydroxide  accelerates  the  development  of  hydroquinone 
giving  soft  contrasts,  while  sodium  carbonate  produces  stronger  contrasts. 
Here  is  a satisfacctory  all  around  solution: 


Water 8 ounces 

Hydroquinone  Y4  ounce 

Potassium  carbonate 3 ounces 

Potassium  bromide 9 ounces 

Sodium  sulphite 2 ounces 


With  normal  exposures  dilute  with  2 to  3 times  its  bulk  of  water. 


METOL. 

Metol  is  an  extremely  rapid  developer  producing  soft  delicate 
negatives.  On  developing  with  Metol  it  will  be  found  to  bring  the 
detail  out  first  and  gradually  builds  up  the  density  afterwards,  and  is 
admirable  for  negatives  where  detail  rather  than  contrast  is  desired. 
If  a dilute  solution  is  used,  a little  potassium  bromide  should  be  added; 
but  for  average  work  this  is  unnecessary. 

The  following  solution  is  recommended  for  all  around  work: 

Metol 35  grains 

Sodium  sulphite  Yl  ounce 

Sodium  carbonate J/2  ounce 

Potassium  bromide  3 grains 

W ater 10  ounces 

This  solution  does  not  keep  quite  as  well  as  others. 


METOQUINONE. 

This  is  an  energetic  developer  and  is  used  with  or  without  the 
usual  alkalies,  Lumiere  suggests  the  following  solution: 

Metoquinone 43  grains 

Sodium  sulphite 1 '/4  grains 

Water  . 10  ounces 

, For  snap  shots  add  about  % ounce  acetone. 


64 


MONOMET. 


This  product  was  introduced  in  the  latter  part  of  1916,  being 
made  in  England.  Its  composition  is  not  known,  the  manufacturers 
say  it  is  a derivitive  of  cresol  and  that  it  is  similar  to  Metol  in  every 
respect.  In  actual  practise  this  was  found  to  keep  better  in  solution, 
negatives  developed  with  it  have  more  density.  The  prints  are  a rich 
carbon  black  instead  of  the  usual  blue  black  of  Metol.  Monomet 
is  extremely  sensitive  to  potassium  bromide. 


ORTOL. 

Ortol  behaves  the  same  as  Pyrogallol,  with  the  exception  that  it 
gives  excellent  black  negatives  and  free  from  stain.  If  made  up  with 
Sodium  sulphite  or  potassium  metabisulphite  it  will  keep  fairly,  well  in 
amber  colored  bottles  and  may  be  used  repeatedly  within  reasonable 
limits,  growing  slower  in  action  each  time. 

For  tank  development  where  various  negatives  with  widely  dif- 
ferent exposures  are  dealt  with  the  following  is  recommended: 


Water 10  ounces 

Potassium  metabisulphite ^Yz  grains 

Ortol  5 grains 

Sodium  sulphite 32 '/i  grains 

Sodium  carbonate 32J/2  grains 


The  time  for  development  is  about  1 5 minutes. 

PARA  AMIDOPHENOL. 

Para  amidophenol  is  a developer  having  remarkable  properties  all 
its  own.  It  is  a curiously  balanced  developer,  in  that  it  can  behave  in  a 
weak  way,  both  as  an  acid  and  a base.  As  a base  it  combines  with 
strong  acids,  such  as  hydrochloric  or  sulphuric  acid,  forming  salts. 
With  strong  alkalies  (sodium  hydroxide)  it  behaves  as  a weak  acid, 
forming  sodium  Para  amidophenolate.  The  first  addition  of  sodium 
hydroxide  precipitates  the  Para  amidophenol  (base)  itself  as  an  insoluble 
compound,  but  this  latter  redissolves  as  more  alkali  is  added,  in  this  way 
a very  concentrated  solution  can  be  made  corresponding  to  Rodinal  of 
commerce. 


65 


Para  amidophenol  (free  base)  with  sodium  sulphite  alone 
develops  very  slowly,  this  being  due  to  the  fact  that  very  little  of  it  is  in 
solution  (on  account  of  its  solubility).  In  order  that  it  may  be  used 
with  little  trouble  it  is  converted  into  a salt  that  is  readily  soluble  in 
water. 

Para  amidophenol  hydrochloride  is  readily  soluble  in  water 
(1:10),  its  keeping  qualities  are  better  in  fairly  strong  solutions  rather 
than  in  dilute  solutions.  It  dissolves  in  a 5 to  10  per  cent  solution  of 
sodium  sulphite  and  keeps  clear,  retaining  its  characteristic  quality  for 
days.  When  made  up  in  developing  solutions  where  the  sodium  car- 
bonate predominates,  para  amidophenol  will  keep  indefinitely. 

When  Para  amidophenol  is  dissolved  in  sulphite  or  carbonate 
solutions,  there  results  a formation  of  the  true  “base”  in  solution.  In 
this  way  the  solution  is  minus  the  Para  amidophenol  and  it  is  said  to 
“slow  up”  or  “run  down”  more  quickly  than  Metol.  On  the  addition 
of  a little  sodium  hydroxide  to  the  solution,  just  enough  to  redissolve  the 
precipitate  first  formed,  it  will  become  effective  again  for  use. 

Many  photographers  advise  to  use  Para  amidophenol  “the  same 
as  Metol,”  i.e.,  replacing  the  amount  of  Metol  for  that  of  Para  amido- 
phenol and  its  salts.  This  is  not  so,  because  Para  amidophenol,  unlike 
Metol,  is  extremely  sensitive  to  the  restraining  action  oi  potassium 
bromide.  In  many  formulas  the  amount  of  bromide  equals  that  of 
Metol  itself.  With  Para  amidophenol  the  proportion  should  rarely 
exceed  1 part  of  potassium  bromide  to  1 0 parts  of  Para  amidophenol. 
Generally  a smaller  quantity  can  be  used  to  advantage. 

Many  photographers  advise  to  use  Para  amidophenol  “the  same  as 
Metol”,  i.  e. ; replacing  the  amount  of  Metol  for  that  of  Para  amido- 
phenol and  its  salts.  This  is  not  so,  because  Para  amidophenol  unlike 
Metol  is  extremly  sensitive  to  the  restraining  action  of  potassium  bromide. 
In  many  formulas  the  amount  of  bromide  equals  that  of  Metol  itself. 
With  Para  amidophenol  the  proportion  should  rarely  exceed  1 part  of 
potassium  bromide  to  1 0 parts  of  Para  amidophenol.  Generally  a smaller 
quantity  can  be  used  to  advantage. 


66 


A developer  advocated  by  Dr.  Liesegang,  who  found  that  citric 
acid  is  an  excellent  solvent  for  Para  amidophenol,  97  parts  by  weight 
of  which  are  soluble  in  200  parts  of  a 50  per  cent,  solution  of  citric 
acid  in  water.  The  Para  amidophenol  should  be  added  gradually  at 
a temperature  of  65  to  68  deg.  F.  The  Para  amidophenol  citrate 
so  formed  is  employed  as  a developer  in  the  following  proportions; 


Para  amidophenol  citrate  (solution) 1 part 

Sodium  sulphite  (concentrated  solution)  ....  5 parts 

Sodium  carbonate 5 parts 

Potassium  hydroxide  (10  per  cent,  solution)  2 parts 

Water  50  parts 


This  is  ready  for  use  and  may  be  employed  repeatedly.  It  gives 
blue  black  images  with  normal  exposures. 

Many  photographers  fail  to  get  sufficient  density  with  Para  ami- 
dophenol or  Rodinal  to  give  good  printing  negatives.  This  is  generally 
due  to  the  fact  that,  with  Para  amidophenol,  as  with  Metol  and  Amidol, 
the  image  appears  rapidly  but  gains  density  slowly.  Also  a little  density 
is  lost  during  the  fixing  process.  The  remedy  is  obvious,  carry  the 
development  a little  further  than  seems  necessary  by  the  usual  visual 
test,  in  order  to  make  sure  of  a negative  of  sufficient  density  to  yield 
good  graduations  in  the  prints. 


PHENYL  HYDRAZINE. 

This  developer  acts  very  weakly  and  for  that  reason  it  is  not  used.  ✓ 

Recently  a small  per  cent  of  Phenyl  hydrazine  was  incorporated 
into  the  negative  during  the  course  of  sensitising,  on  development  it  was 
found  to  prevent  “halation”  to  a great  extent.  In  fact  this  idea  is  used 
in  the  manufacture  of  the  non  over  expoure  negatives  called  in  com- 
merce “Hydra”  plates. 


67 


PARA  PHENYLENEDIAMINE. 

This  developer  is  not  so  popular  here  in  America  as  it  is  in  Europe, 
due  perhaps  to  the  lack  of  definite  information  concerning  it.  It  is  a 
slow  working  developer  giving  good  details  in  the  shadows  with  a 
brownish  black  print,  free  from  fog  or  stain. 

Brewster  advocates  the  following  formula: 


Para  phenylenediamine  10  grains 

Sodium  sulphite  10  grains 

Sodium  nitrite 10  grains 

Sodium  carbonate 2 grains 

Water  8 ounces 


This  solution  works  quite  rapid  and  will  keep  well  for  a long  time. 

PHENYL  HYDROXYLAMINE. 

This  compound  acts  vigorously  as  a developer,  but  is  of  no  prac- 
tical use  as  nitrogen  gas  is  evolved  during  development,  this  reticulates 
and  pits  both  the  negative  and  prints. 

For  the  benefit  of  those  who  might  want  to  try  this  developer  the 


following  is  suggested: 

Phenyl  hydroxylamine  hydrochloride.*.  ....  2 grains 

Sodium  hydroxide 3 grains 

Potassium  bromide j/2  grain 

Water 1 ounce 


This  developer  should  be  used  only  once  and  the  negatives  washed 
thoroughly. 


PYRAMIDOL. 

This  developer  is  particularly  admirable  for  developing  negatives 
of  gross  over  exposures.  It  will  develop  much  the  same  as  Amidol 
without  the  use  of  the  usual  alkalies.  The  following  solution  is  found 


to  give  satisfactory  results: 

(A)  Sodium  sulphite 1 1^2  ounces 

Pyramidol 90  grains 

Water 20  ounces 

(B)  Potassium  carbonate 1 ounce 

Water 29  ounces 


For  use  mix  A and  B in  equal  proportions. 


68 


PYROCATECHIN. 


This  developer  gives  clear  printing  negatives  with  less  density  and 
no  greater  detail  for  a given  exposure  than  Pyrogallol  or  Hydroquinone, 
but  has  the  advantage  that  it  works  well  in  dilute  solutions. 

A curious  and  valuable  property  possessed  by  Pyrocatechin  is  that 
it  gives  better  results  with  stale  negatives  than  any  other  developer. 

The  following  solution  is  recommended  for  all  around  work: 

Pyrocatechin 120  grains 

Sodium  sulphite 4.80  grains 

Citric  acid 20  grains 

Water  . 10  ounces 

Vogel  first  discovered  that  Pyrocatechin  will  develop  in  the  pres- 
ence of  hypo  and  that  it  may  be  used  to  simultaneously  develop  and  fix 
the  image;  the  following  solution  was  suggested  by  him:  ^ 


Sodium  sulphite 468  grains 

Potassium  hydroxide 108  grains 

Pyrocatechin  108  grains 

Water  3 ounces 


Take  of  this  solution  3 drams  and  dilute  with  1 ounce  of  water 
and  add  drams  of  a 1.5  hypo  solution. 

Fixing  and  developing  is  complete  in  a few  minutes. 


PYROGALLOL. 

Pyrogallol,  the  oldest  organic  developer,  is  at  the  present  day  still 
used  very  extensively.  The  fine  gradations  of  the  negative,  the  great 
power  of  variations  for  errors  in  exposure,  are  properties  which  have 
created  a lasting  place  for  Pyrogallol,  although  it  quickly  spoils  when 
exposed  to  the  air. 

Pyrogallol  has  not  the  characteristic  properties  of  an  acid — it 
has  a bitter,  not  a sour  taste  and  it  does  not  redden  blue  litmus — hence 
chemists  do  not  consider  it  as  a true  acid  ajjd  in  chemical  text  books  it 
is  now  termed  “Pyrogallol,”  but  to  photographers  it  is  familiarly  known 
as  “Pyrogallic  acid”  and  also  as  “Pyro.” 


69 


PYROGALLOL  ACETONE. 


Commercially  it  comes  in  two  forms,  resublimed  and  in  crystals. 
Of  the  two  forms,  photographers  prefer  to  use  the  latter  as  it  is  easier 
to  handle. 

In  solution,  its  keeping  qualities  are  very  poor,  for  this  reason  it  is 
preferred  to  be  made  up  before  it  is  ready  for  use. 

Potassium  bromide  has  a ready  and  energetic  effect  in  restraining 
the  developing  action  of  Pyrogallol. 

This  developer  yields  a brilliant  negative  with  a rich  gradation 
from  intense  high  lights  to  clear  shadows,  it  consists  of: 

Pyrogallol  30  grains 

Sodium  sulphite 120  grains 

Acetone  — 40  minims 

Water  12  ounces 

This  solution  is  intended  for  tray  development  and  the  development 
is  complete  in  about  6 minutes.  For  tank  development  the  amount  of 
water  can  be  increased  to  30  ounces  and  the  time  for  development  will 
be  about  30  minutes. 


PYROGALLOL  SODA  TANK  DEVELOPER. 

The  Eastman  Kodak  Co.  advocates  the  following  receipe,  the 
outstanding  features  claimed  for  this  solution  is  its  excellent  keeping 
qualities  and  the  production  of  remarkably  clear  negatives.  The  for- 


mula is: 

Pyrogallol  2 ounces 

Sodium  sulphite  (neutral) 20  ounces 

Potassium  metabisulphite  2J/2  ounces 

Sodium  carbonate TYl  ounces 

Water  to 280  ounces 


The  following  instructions  must  be  strictly  followed,  as  the  keeping 
qualities  of  this  developer  depends  entirely  upon  the  method  of  making 
it  up. 


70 


Dissolve  the  sodium  sulphite  in  60  ounces  of  hot  water  (not  boil- 
ing). When  dissolved,  add  the  potassium  metabisulphite  and  then 
boil  for  5 minutes.  Cool  down  to  about  70  deg.  F.  and  add  the 
h'yrogallol.  Dissolve  the  sodium  carbonate  in  20  ounces  of  warm  water. 
Pour  these  two  solutions  into  the  tank  and  make  up  to  280  ounces  of 
water.  The  time  for  development  is  about  1 8 minutes  at  65  deg.  F. 

An  acid  fixing  bath  should  always  be  used. 

REDUCIN. 

Reducin  works  like  Amidol,  the  following  solution  is  recommended 
by  Vogel: 

Reducin  26  grains 

Sulphuric  acid  5 minims 

Sodium  sulphite 218  grains 

Water  10  ounces 

This  solution  keeps  well  in  amber  colored  bottles. 

RODINAL. 

The  use  of  Para  amidophenol  in  the  form  of  a concentrated  solu- 
tion has  attained  wide  popularity,  such  solutions  only  requiring  dilution 
for  use.  Rodinal,  which  was  the  first  commercial  form  of  Para  ami- 
dophenol, has  subsequently  had  other  competitors  and  though  as  far  as 
I am  aware,  the  base  of  these  other  single  solution  developers  has  not, 
in  any  case  of  any  any  one  of  them,  mentioned  as  Para  amidophenol, 
it  may  be  taken  that  it  is  this  compound  which  is  used. 


HOW  RODINAL  IS  MADE. 

Several  years  Desalme  in  a paper  before  the  French  Photographic 
Society,  gave  working  instructions  for  making  a solution  similar  to 
Rodinal.  I cannot  do  better  than  give  his  directions.  Make  a solution 


of: 

Para  amidophenol  hydrochloride 7^  ounces 

Water  (hot)  60  ounces 

Now  prepare  the  following: 

Sodium  carbonate  ouncgs 

Sodium  sulphite  1 ounce 

Water  (warm)  20  ounces 


71 


add  this  solution  to  the  above,  a precipitate  of  Para  amidophenol  will 
form.  It  is  allowed  to  cool  and  filtered  through  a linen  bag,  from  which 
as  much  water  as  possible  is  allowed  to  drain.  The  bulk  of  the  paste 
thus  formed  should  not  be  more  than  30  ounces. 

Dissolve  the  paste  in  10  ounces  sodium  bisulphite  (25  deg.  Be.) 
and  then  add  little  by  little  a strong  solution  of  sodium  hydroxide  (5 
ounces  and  sufficient  water  to  make  a bulk  of  1 0 ounces) , stirring  all 
the  time.  The  paste  will  gradually  dissolve.  Great  care  must  be 
taken  not  to  add  too  much  of  this  alkali.  After  this  the  bisulphite  solu- 
tion is  added  to  give  a slight  permanent  precipitate.  Water  is  now 
added  to  make  a total  bulk  of  50  ounces  and  the  solution  is  ready 
for  bottling  in  which  it  keeps  excellently.  To  form  the  working  solution 
it  is  mixed  from  20  to  40  times  its  bulk  of  water. 

For  average  negative  work  a dilution  with  20  parts  of  water  is 
about  the  best,  but  many  photographers  prefer  to  dilute  it  with  1 0 parts 
of  water,  in  order  to  get  ample  density. 

Another  concentrated  one  solution  developer  like  Rodinal  may  be 


made  from: 

Potassium  metabisulphite  ^ ounce 

Para  amidophenol '/4  ounce 

Water  (hot)  21/2  ounces 


Dissolve  in  the  order  given  tand  add  slowly  a comcentrated 
solution  of  sodium  hydroxide  until  the  precipitate  first  formed  is  dis- 
solved. For  use,  dilute  with  1 0 to  30  parts  of  water,  an  average  strength 
being  24  drops  to  each  ounce  of  water. 


SYNTHOL. 

Synthol  is  used  in  the  same  way  as  Amidol,  a typical  solution 


consists  of: 

Water 10  ounces 

Sodium  sulphite 300  grains 

Synthol  30  grains 

Potassium  bromide 5 grains 


This  solution  will  give  good  snapy  prints. 


72 


9 


CHAPTER  II. 


FACTORIAL  DEVELOPMENT. 

The  factorial  system  of  developing  was  originally  suggested  by 
Alfred  Watkins  in  1893,  its  object  is  to  determine  the  time  of  develop- 
ment. 

This  is  done  by  noting  the  time  it  took  to  produce  the  first  trace 
of  an  image  on  the  negative  and  multiplying  this  time  by  a given  factor, 
the  result  being  the  total  duration  of  development  required  to  produce  a 
negative  of  given  density. 

Only  experienced  photographers  can  determine  the  exact  time  to 
stop  development,  this  they  ascertain  by  judging  the  negative  aS  it  is 
being  developed.  With  the  factorial  system  of  development  all  that 
requires  to  be  done  is  to  calculate  the  time  as  already  described  and 
after  the  expiration  of  this  time  the  negative  is  removed  and  ready  to  be 
fixed. 

This  system  has  been  found  to  be  very  reliable  in  actual  practise 
and  in  fact  one  large  motion  picture  laboratory  uses  this  system 
throughout,  in  this  way  they  are  enabled  to  produce  negatives  and  posi- 
tives of  equal  density. 

Every  developer  irrespective  of  concentration  and  composition  of  its 
solution,  has  a specific  ratio  between  the  time  required  for  the  negative  to 
assume  all  the  contrast  possible  in  the  given  circumstances  and  the  time 
required  for  the  image  to  make  its  appearance  after  inmersion  in  the 
developer.  This  ratio  is  known  as  its  “factor  . Like  all  physical  laws,  it 
elastic  and  capable  of  adjustment  tto  tthe  individual  requirements  and 
ideas  of  what  is  a correct  negative,  or,  in  other  words  by  reducing  or 
increasing  the  factor  a thinner  or  denser  negative  may  be  obtained. 


73 


The  following  factors  are  those  generally  used  for  the  principal 


developers 

Adurol  5 

Amidol 8 

Edinol  20 

Eikonogen  9 

Glycin  8 

Hydroquinone 5 

Metol  30 

Ortol  10 

Para  amidophenol 16 

Pyrocatechim  10 

Quinomet  30 

Rodinal  30 


To  illustrate  this  fact  we  might  use  Metol  as  the  developer,  it 
will  be  found  to  produce  the  first  trace  of  an  image  in  1 0 seconds.  The 
developing  factor  of  Metol  is  30,  now  therefore  multiply  the  time  of  the 
first  trace  of  the  image  with  the  factor,  the  result  is  300  seconds  or 
exactly  5 minutes.  If  the  worker  will  look  on  the  negative  at  the  expira- 
tion of  that  time  he  will  find  the  negative  to  be  of  correct  density. 


THE  FACTOR  OF  PYROGALLOL. 

Pyrogallol  and  Amidol  are  exceptions  to  the  rule,  being  dependant 
on  the  number  of  grains  to  the  alkaline  solution  and  also  on  the  quantity 
of  potassium  bromide  used.  The  following  table  will  enable  the  factor 
of  any  Pyrogallol  developing  solution  to  be  readily  calculated,  provided 
of  course  the  formula  is  known. 


Grains  of 

F actor 

Grains  of 

Factor 

Pyrogallol 

without 

bromide 

with 

per  ounce 

bromide 

per  ounce 

bromide 

I 

18 

/4 

9 

2 

12 

!/2 

5 

3 

10 

4/2 

4 

8 

1 

4 

5 

6/2 

2 

3 

74 


THE  FACTOR  SIX. 


A developer  having  6 as  its  factor  is  very  convenient  to  work  with, 
all  we  must  do  is  to  divide  the  time  of  the  first  appearance  of  the  image 
by  1 0 to  obtain  the  number  of  minutes,  thus  saving  the  time  of  dividing 
by  60.  For  example,  if  the  time  of  appearance  is  20  seconds,  by  the 
ordinary  method  the  calculation  would  be  20  times  6 equal  1 20  divided 
by  60  equal  2 minutes,  whereas  by  the  quicker  method  it  is  20  divided 
by  1 0 equal  2 minutes. 

THE  FACTOR  OF  COMBINED  DEVELOPERS. 

The  factor  for  a combined  developer  with  the  agents  in  equal 
proportions  will  be  practically  equal  to  the  average  or  mean  of  their 
constituents.  For  example,  equal  parts  of  Hydroquinone  and  Metol 
would  have  a factor  of  about  \ lYi.  When  two  developers  are  used 
in  unequal  proportions  the  calculations  are  done  somewhat  differently. 
Thus  with  a mixture  of  3 parts  Metol  to  2 parts  Hyroquinone,  the 
factor  would  be  found  as  follows: 

Metol  (3  parts)  30X3=90 
Hydroquinone  (2  parts)  5x2=10 

90  plus  1 0 equal  1 00  divided  by  5 equal  20,  the  required  factor. 

Supposing  one  were  using  a Metol-Hydroquinone  developer  with 
a factor  of  1 5 and  the  timfe  of  appearence  were  9 seconds,  the  total' 
duration  of  development  would  be  1 5 times  9 equal  1 35  seconds  or 
2|/2  minutes. 

The  advantage  of  the  factorial  system  of  development  over  the 
visual  is  obvious  in  that  it  reduces  a rule  of  thum  method  to  that  of  an 
exact  one. 


75 


CHAPTER  III. 

BLEACHING  AND  INTENSIFICATION. 

There  are  a number  of  occasions  that  poor  negatives  are  obtained, 
due  perhaps  to  an  incorrect  exposure  or  development.  Or  in  other  cases 
the  negative  is  found  to  be  too  opaque,  due  to  an  over  exposure  or  a 
continued  development.  In  the  first  case  the  negative  is  said  to  be  too 
“thin”  and  requires  intensification,  the  second  case  requires  “reduction’’ 
or  “bleaching”  in  order  to  make  a decent  print  of  it. 

Before  bleaching  or  intensification  is  carried  on,  the  negatives  must 
be  perfectly  free  from  hypo  and  also  the  so-called  “dichroic  veil.” 

The  hypo  is  best  disposed  of  by  continued  washing,  it  is  well  to 
test  this  from  time  to  time,  in  order  to  get  the  best  results  and  free  from 
chemical  coloration. 

DICHROIC  VEIL. 

This  defect  is  produced  by  a lengthened  development,  or  by  an 
excess  of  developer  in  the  fixing  solution.  This  causes  the  high  lights 
of  the  prints  to  become  fluorescent  and  blocked.  It  is  readily  removed 
in  any  of  the  following  solutions: 


Water 

Example  /. 

. 10 

ounces 

Sodium  bisulphite 

. 5 

grains 

Water 

Example  II. 

10 

ounces 

Alum  

1 

ounce 

Thiocarbamide  . 

Example  III. 

. . 1 

dram 

Alum  

1 

dram 

Citric  acid  .... 

1 

dram 

Water 

..  10 

ounces 

The  negative  should  immediately  be  removed  after  the  high 
lights  are  found  to  be  perfectly  clear.  It  is  now  washed  in  running  water 
and  allowed  to  dry. 


76 


TEST  FOR  HYPO. 


The  following  receipe  is  one  of  the  oldest  and  yet  reliable  methods 
of  testing  for  the  presence  of  minute  traces  of  hypo.  The  test  solution 


consists  of: 

Potassium  permanganate  5 grains 

Sodium  hydroxide 20  grains 

Water 5 ounces 


A few  drops  of  this  solution  is  added  to  from  1 0 to  20  ounces  of 
water.  The  negative  or  print  that  is  to  be  tested  for  hypo  is  allowed 
to  drip  or  soak  in  the  above  solution.  The  water  will  remain  a pinkish 
tinge  for  some  time,  but  if  there  is  a slight  amount  of  hypo  present,  the 
solution  rapidly  assumes  a greenish  tint.  The  strength  of  the  solution 
should  not  be  exceeded  or  the  delicacy  of  the  test  is  impaired. 

This  test  should  be  repeated  until  no  reaction  is  seen,  thus  indicat- 
ing that  there  is  no  hypo  present  in  the  print  or  negative. 

HARDENING. 

Some  photographers  make  it  a practice  of  hardening  the  negative 
or  print  after  it  is  fixed.  This  is  advisable  in  the  summer  time,  sincd 
it  prevents  the  surface  from  frilling.  Here  are  two  solutions  found  to 


give  satisfactory  results: 

Example  /. 

Formaline  1 ounce 

Water  30  ounces 

Example  II. 

Alum 8 ounces 

Acetic  acid  20  ounces 

Sodium  sulphite 3 ounces 

Water  20  ounces 


These  solutions  can  be  used  over  and  over  again,  as  its  keeping 
qualities  are  excellent. 

BLEACHING. 

There  are  a great  number  of  compounds  used  in  bleaching  and 
intensification,  some  are  modifications  of  others.  Each  one  of  these 
processes  has  its  own  characteristics  and  find  some  special  advantage 
for  a particular  purpose. 


77 


MERCURY  CHLORIDE. 

Of  all  the  bleaching  solutions  in  use,  there  is  none  as  popular  as 
that  mailing  use  of  mercury  chloride.  A typical  solution  being: 


Mercury  chloride  105  grains 

Water  8 ounces 

Ammonium  chloride 42  grains 


The  bleaching  action  taking  place  immediately  due  to  the  fact 
that  a chlorine  radicle  is  being  split  off  from  the  mercury  chloride  and 
attaches  itself  to  the  silver  image,  forming  white  silver  chloride  and 
mercurous  chloride  (calomel),  thus: 

2Ag+2HgC12=2AgCl+Hg2CP. 

Mercury  solutions  are  extremely  poisonous  and  great  care  should 
be  used  in  handling  this. 


MERCURY  IODIDE. 

Edwards  was  the  first  to  publish  the  use  of  mercuric  iodide  dis- 
solved in  hypo  as  a direct  intensifier  for  negatives. 

Later,  Vogel  slight^  modified  the  composition  of  Edwards’  solu- 
tion. According  to  these  investigators,  the  solution  consists  of: 


Mercury  bichloride  4 grams 

Hypo 8 grams 

Potassium  iodide 10  grams 

Water 4 ounces 


This  solution  can  be  used  repeatedly  until  exhausted. 

After  intensification  the  negative  should  be  washed  so  as  to  cause 
the  maximum  formation  of  yellow  mercuric  iodide.  This  yellow  iodide 
must  then  be  thoroughly  removed  in  a weak  hypo  solution,  which  should 
be  allowed  to  act  on  it  until  no  yellowness  is  visible  on  examination  of 
the  glass  side  of  the  negative.  For  this  reason  the  intensification  should 
be  done  only  in  day  light,  otherwise  it  is  not  easy  to  tell  when  the  yellow 
iodide  has  been  perfectly  disposed  of.  The  results  prove  quite  permanent 
when  these  precautions  are  taken.  If  the  negative,  on  drying,  proves 
to  be  too  dense,  it  can  be  reduced  to  some  extent  by  immersion  in  the 
ordinary  fixing  solution. 


78 


Here  are  two  modified  and  simple  formulas: 
Example  I. 


Mercury  iodide  

15 

grains 

Sodium  sulphite 

300 

grains 

Water 

3/2 

ounces 

Example  II. 

Mercury  chloride 

54 

grains 

Potassium  iodide  

33 

grains 

W ater 

8 

ounces 

BLEACHING  WITH  THE  FERRICYANIDES. 

Besides  the  mercury  salts  those  of  the  ferricyanides  produce 
equally  good  results,  in  fact,  in  some  processes  as  for  toning  it  is 


preferable. 

Here  are  a few  typical  solutions ; 

Example  /. 

Potassium  ferricyanide 20  grains 

Potassium  bromide 30  grains 

Water  5 ounces 

Example  II. 

Potassium  ferricyanide  I grain 

Potassium  iodide  1 grain 

Water 5 ounces 

Example  III. 

Potassium  ferricyanide 75  grains 

Ammonium  bromide 25  grains 

Water 5 ounces 

Example  IV. 

Potassium  ferricyanide  1 ounce 

Chromic  acid 1 ounce 

Water 1 gallon 

Example  V. 

Potassium  ferricyanide 12  grains 

Sodium  phosphate  12  grains 

Water  5 ounces 

79  , 


Example  VI. 


Potassium  iodide  15  grains 

Iodine  8 grains 

Water 10  ounces 


FARMER’S  REDUCER. 

This  solution  is  very  popular  and  consists  of: 


Potassium  ferricyanide  3 grains 

Hypo 30  grains 

Water 4 ounces 


Inasmuch  as  this  solution  does  not  keep  well  it  is  prepared  before 
it  is  intended  to  be  used. 

Gear,  in  the  course  of  his  experiments  on  the  addition  of  various 
substancecs  to  Farmer’s  reducer  (hypo  ferrocyanide)  for  the  purpose 
of  prolonging  the  time  during  which  the  reducecr  retains  its  activity,  has 
found  that  on  the  addition  of  4 grains  potassium  bromide  to  each  ounce 
of  the  mixed  reducer  prolongs  the  time  during  which  the  reducer  keeps 
in  working  condition  by  about  30  per  cent. 

Brougham  finds  that  the  addition  of  ammonium  sulphocyanide  to 
Farmer’s  reducer  prolongs  the  time  of  effective  action.  He  makes  10 
per  cent  stock  solutions  and  uses  of  them  as  follows: 


Potassium  ferricyanide 2 drams 

Hypo 2 drams 

Ammonium  sulphocyanide  ........  2 drams 

Water  2 ounces 


The  keeping  qualities  of  this  solution  it  is  found  to  be  good. 

POTASSIUM  PERMANGANATE. 

Next  in  importance  comes  the  potassium  permanganate  intensifier. 
This  gives  excellent  results  and  very  great  intensification  can  be  obtained 
with  it,  the  image  being  black.  With  a weak  acid  solution  of  potas- 
sium permanganate  the  image  turns  pinkish  yellow  and  after  washing 
and  redeveloping  with  Hydroquinone  or  Metol-Hydroquinone,  the 
bleached  image  again  becomes  black  and  the  density  is  thus  obtained. 


80 


A typical  solmtion  suggested  by  Namias  is: 


Potassium  permanganate 123  grains 

Water 34  ounces 

Water 34  dunces 


Keep  this  stock  solution  in  an  amber  colored  glass  stoppered  bottle. 
For  use  dilute  1 part  of  the  solution  with  30  parts  of  water. 

This  bleaching  solution  finds  application  for  negatives  of  normal 
strength.  The  bleaching  action  is  extremely  rapid.  When  the  right 
degree  of  bleaching  has  been  obtained,  the  negative  should  be  immedi- 
ately placed  in  the  following  solution : 


Water 3 ounces 

Sodium  bisulphite 2 grains 


Which  will  eliminate  the  yellow  tint  of  the  manganese  dioxide, 
after  which  the  negative  should  be  wadiel  for  1 5 to  30  minutes  and 
dried. 

The  bleached  negative  is  redeveloped  the  same  as  is  done  in  the 
case  of  the  chromium  bleacher. 


AMMONIUM  PERSULPHATE. 

This  solution  is  a simple  one  to  prepare  and  consists  of: 


Ammonium  persulphate  15  grains 

Water  1 ounce 


This  solution  attacks  the  high  lights  without  affecting  the  detail 
in  the  shadows. 

Hunter  recommends  a mixture  of  the  Farmer  and  ammonium  per- 
sulphate reducer.  By  adding  1 part  ammonium  persulphate  ( 1 to  20) 
to  3 or  4 parts  of  the  Farmer  reducer  we  obtain  a proportional  reducer 
as  near  perfection  as  there  is  any  need  for.  The  combined  reducer  does 
not  stain  like  the  Farmer  reducer  by  itself;  it  acts  very  quickly,  especially 
if  negatives  are  put  in  dry;  there  is  no  need  for  sodium  chloride  or 
sodium  sulphoccyanide  to  keep  it  in  working  order  longer;  one  solution 
will  reduce  a dozen  or  more  negatives  in  succession  and  there  is  no  need 
for  a sodium  sulphite  stop  solution. 


81 


Deck  recommends  the  following  solution: 

Potassium  permanganate  ( 1 per  cent,  solution)  ....  20  minims 


Ammonium  persulphate 10  grains 

Water  to 2 ounces 


This  reducer  should  preferably  be  made  up  just  before  use. 

The  reducer  is  found  to  have  the  following  advantages:  The 

action  starts  at  once  and  is  regular,  that  is  it  does  not  spurt  towards 
the  end  like  ammonium  persulphate.  Hypo  in  the  negative  through 
imperfect  washing  does  not  interfere  with  it.  The  solution  is  not  liable 
to  fail  in  its  action  at  times  from  some  unknown  cause;  also  it  is  easier 
to  judge  of  the  action  than  with  potassium  permanganaije  alone  and 
the  solution  appears  to  remain  active  working  longer  than  acid  perpian- 
ganate.  So  far  as  can  be  judged  from  trials,  its  action  is  proportional 
throughout  the  tones  of  the  negative. 

COPPER  BROMIDE. 

The  copper  solutions  bleach  quite  well.  Here  are  some  popular 
receipts : 

^ Example  /. 


Copper  sulphate 1 ounce 

Sodium  chloride 1 ounce 

Water 25  ounces 


When  dissolved  add  enough  ammonia  (.880)  to  clear  the  solution, 
which  should  be  a ricch  ultramarine  color. 


Example  II. 

Copper  sulphate 30  grains 

Potassium  bromide 30  grains 

Water 7 ounces 

Example  III. 

Cupric  chloride 180  grains 

Hydrochloric  acid  20  minims 

Water 20  ounces 

These  solutions  keep  well: 


LEAD  NITRATE. 

With  lead  nitrate  the  silver  image  is  converted  into  lead  and  silver 
ferrocyanide : 

3Pb3Fe2Cn2  4Agi2  3Pb2Fe(Cn)6  2AgFeHCn)6. 

Here  are  two  typical  solutions: 


82 


Example  I. 

Potassium  ferricyanide  6 grains 

Lead  nitrate 4 grains 

Water 10  ounces 

Example  II. 

Potassium  ferricyanide  600  grains 

Lead  nitrate 400  grains 

Acetic  acid  1 dram 

Water  20  ounces 


Example  II  consists  of  a stock  solution,  this  will  keep  well  for  a 
long  time  in  amber  colored  bottles  and  preferably  in  the  dark.  The 
negative  after  bleaching  is  washed  once  very  carefully  in  a 1 0 per  cent 
nitric  acid  sblution,  then  in  running  water  and  darkened  in  any  of  the 
intensifying  solutions  given. 

The  lead  intensifying  solutions  permits  great  intensification  and 
increases  the  harshness  of  the  negative. 


CHROMIUM 

In  this  process,  which  was  worked  out  in  detail,  though  not 
actually  invented,  by  Piper  and  Carnegie  (Amature  Photo,  page  366, 
1904,  page  453,  1905),  the  negative  is  treated  with  a solution  of 
potassium  bi-chromate  acidified  with  hydrochloric  acid  and  the  bleached 
image,  after  washing,  is  treated  or  darkened  with  an  ordinary  developer. 
According  to  these  investigators,  the  bleached  image  consists  of  a 
chromium  compound,  which  they  suggest  may  be  the  so  called  chromium 
dioxide  CrO^,  generally  regarded  as  cromic  chromate  Cr^C®.  They 
established  the  presence  of  chromium,  but  not  the  precise  nature  of  the 
chromium  compound. 

The  three  working  formulas  recommended  by  Piper  and  Carnegie 


are: 

A 

B 

C 

Potassium  bichromate  . . 
Hydrochloric  acid 

. . . . 5 grains 

1 0 grains 

10 

grains 

(sp.  gr.  1.1 60) 

. . . . 1 minim 

5 minims 

20 

minims 

W ater 

1 ounce 

1 

ounce 

They  found  that  formula  A gives  a high  degree  of  intensification, 
formula  C a low  degree,  whilst  formula  B gives  an  intermediate  result. 

83 


The  chromium  salts  are  of  great  practical  value,  as  many  have 
already  recognized,  it  is  easy  to  work  and  if  great  care  is  taken  in  mak- 
ing up  the  solution  it  will  give  concordant  results.  Moreover,  it  is  ap- 
plicable to  negatives,  lantern  slides  and  bromide  or  prints.  Formula  C 
not  only  gives  that  slight  degree  of  intensification  which  a print  often 
needs,  but  may  also  greatly  improve  the  color  of  the  image.  With  a 
still  larger  proportion  of  acid  there  is  still  less  intensification,  but  at  the 
same  time  a distinct  improvement  of  color,  if,  for  example,  the  original 
image  has  had  the  well  known  olive  green  tint. 

CALCIUM  CHROMATE. 

A less  stable  chromium  salt  may  be  used  in  order  to  accelerate  its 
bleaching  action,  for  this  purpose  calcium  chromate  is  used,  the  following 
is  a typical  receipe: 

Calcium  chromate  1.5  grams 

Hydrochloric  acid  1.5  grams 

Water 100  grams 

About  three  minutes  immersion  in  this  solution  will  suffice;  the 
negative  is  then  thoroughly  washed  and  redeveloped  in  a Hydroquinone 
solution.  A few  minutes  washing  is  necessary  after  development. 

CERIC  SULPHATE. 

This  bleaching  solution  was  originally  introduced  by  Lumiere  in 
the  form  of  a concentrated  solution.  It  can  be  readily  made  of: 


Ceric  sulphate  1 ounce 

Sulphuric  acid  (1.84) 20  minims 

Water 10  ounces 


Hard  negatives  are  placed  in  a mixture  of  this  stock  solution  and 
diluted  with  nine  times  its  volume  of  water.  It  reduces  contrast.  Over 
exposed,  long  developed  negatives  are  dipped  dry  into  a mixture  of  the 
stock  solution  and  an  equal  part  of  water  and  carefully  watched  as  the 
action  is  very  rapid. 

INTENSIFICATION. 

The  following  solutions  consists  of  such  compounds  that  will 
intensify  the  bleached  image.  It  is  well  to  wash  the  bleached  image 
before  intensification  is  carried  on. 


84 


SODIUM  SULPHITE. 

By  treatment  with  sodium  sulphite,  the  following  takes  place: 

2Hg2CP+4HgCl=8Na2S03=Ag2+Hg+8NaCl+ 

3Hg  (NaSQS)  2+2AgNaSQ3. 

The  blackened  image  consists  of  mercury  and  silver. 

A typical  solution  being: 

Sodium  sulphite  1 ounce 

Water  10  ounces 

This  solution  will  keep  fairly  well. 

SODIUM  SULPHIDE. 

By  treatment  with  any  soluble  sulphite  as  sodium,  potassium,  am- 
monium, barium,  etc.,  the  reaction  taking  place  being: 

Hg2CP+2AgCl+2(NH^)2S=rHg2S+Ag2S-f4NH^Cl. 

The  blackened  image  consists  of  a mixture  of  mercurous  and  silver 
sulphides. 

The  solution  consists  of: 

Sodium  sulphide 1 dram 

Water  3J/2  ounces 

This  solution  should  be  fresh  in  order  to  secure  the  best  results. 

AMMONIUM  SULPHIDE. 

On  treating  the  bleached  image  (using  the  ferrocyanides)  with 
ammonium  sulphide,  the  two  salts  become  converted  into  black  sulphides 
as  follows: 

Pb^Fe  (Cn)  6+ AgFe  (Cn)  6+4  (NH^)  2S=2PbS+2  AgSS+ 
2(NH^)'Te(Cn)6. 

A typical  solution  consists  of: 


Water 10  ounces 

Ammonium  sulphite 3 grains 


This  solution  should  be  made  up  before  it  is  to  be  used,  as  its 
keeping  qualities  are  very  poor. 

AMMONIA. 

By  treatment  with  ammonia  dimercurous  ammonium  chloride  is 
'formed  : 

Hg2CF+NH3=NH2Hg2Cl+NH^^HCl. 

The  solution  consists  of: 


Ammonia  (.880)  20  drops 

Water  1 ounce 


This  solution  gives  great  intensification  and  a good  black  color. 

85 


SILVER  NITRATE. 

After  the  negative  has  been  completely  bleached  in  the  copper 
bleacher  it  is  then  washed  in  five  changes  of: 

Sodium  sulphite 50  grains 

Sulphuric  acid 100  minins 

Water  20  ounces 

The  immersion  should  be  for  about  three  minutes  in  the  first 
change  and  for  four  in  the  subsequent  ones.  After  this  washing  has 
been  carried  out,  the  negative  is  immersed  in  a dish  of  water  for  about 
five  seconds  and  then  placed  in: 

Silver  nitrate  80  grains 

Nitric  acid 80  minins 

W ater 10  ounces 

and  then  left  there  until  all  action  is  at  an  end.  The  action  taking  place 
in  the  silver  solution  is: 

Cu^Br^x  4 AgNQ3=2Cu  (NQ3)  2+  (2  Ag+2AgBr) . 

We  get  thus  an  image  consisting  of  silver  bromide  and  a silver 
and  silver  sub-bromide. 

The  negative  is  now  thoroughly  washed  and  after  this  bleached 
in  bichromate  bleaching  solution.  It  is  then  redeveloped. 


FERROUS  OXALATE. 

By  treatment  with  ferrous  oxalate  the  following  takes  place: 
Hg2CF+2AgCl+4FeC20^+4K2C20i=Ag2-fHg 
+Fe(C20^)3+KCl. 

The  blackened  image  consists  of  silver  and  mercury. 

The  following  is  a typical  solution  made  use  of  in  practise: 

Ferrous  oxalate  5 grains 

Water 10  ounces 

Since  this  solution  does  not  keep  well  it  is  best  that  fresh  solutions 
should  be  made  as  is  required. 


HYPO. 

An  ordinary  hypo  fixing  solution  will  blacken  the  bleached  image. 
Here  is  a typical  solution  made  use  of: 

Hypo 4 ounces 

Water  20  ounces 

This  solution  keeps  well  and  may  be  used  repeatedly.  ^ 


86 


COPPER  SULPHATE. 


The  bleached  and  washed  print  is  placed  in: 

Copper  sulphate  100  grains 

Water  3 ounces 

This  solution  keeps  well  and  is  therefore  kept  in  bottles  ready  to 
be  used. 


URANIUM  NITRATE. 

The  bleached  print  is  washed  in  running  water  and  intensified  in: 

Uranium  nitrate  40  grains 

Acetic  acid  27  minims 

Water 10  ounces 

The  high  lights  will  be  found  to  be  a brownish  tint,  this  is  disposed 
of  by  placing  the  negative  before  the  final  wash  in  a 5 per  cent,  solution 
of  ammonium  sulphocyanide.  Washing  is  carried  on  for  about  2 minutes 
only. 


SCHLIPPE’S  SALT. 

This  solution  should  be  prepared  just  before  it  is  to  be  used: 

Schlippe’s  salt  150  grains 

Water 10  ounces 

The  intensification  is  very  great  and  yields  a nice  warm  brown 

tone. 

ALKALINE  DEVELOPERS. 

Alkaline  developing  solutions  may  be  used  with  equally  good  re- 
sults for  blackening  the  bleached  negative. 


AMMONIUM  MOLYBDATE. 

A solution  of  ammonium  molybdate  and  potassium  ferricyanide 
acidified  with  acetic  acid  also  produces  alteration  of  the  image,  but  the 
slight  Increase  in  density  obtained  is  not  in  favor  of  its  use. 


87 


CHAPTER  IV. 


TONING. 

Toning  is  a chemical  process  in  which  the  black  silver  image  is 
converted  into  a colored  one.  There  are  two  such  processes  in  existence, 
the  first  is  to  bleach  the  image  in  the  usual  manner  already  described, 
using  preferably  any  of  the  ferricyanide  solutions  given,  then  transfer- 
ring the  bleached  print  into  the  toning  solution  after  which  it  is  washed 
and  dried.  The  second  process  consists  of  preparing  a combined  bleach- 
ing and  toning  solution  in  which  the  print  is  steeped  until  the  desired 
tone  is  obtained.  The  solution  of  the  latter  process  unfortunately  does 
not  keep  well  and  is  sensitive  to  light.  The  former  process  is  easily 
controlled  and  keeps  indefinitely. 

Before  the  toning  is  carried  on  a word  or  two  regarding  the  prints 
proper  will  not  be  amiss.  The  prints  must  be  perfectly  free  from  hypo 
and  other  chemicals,  otherwise  the  tone  will  not  be  perfect  throughout. 

Prints  should  be  fully  exposed  but  slightly  under  developed,  as 
all  the  toning  solutions  will  intensify  the  print  and  produce  flat  images 
and  clogged  high  lights.  After  toning  is  finished  the  print  should  be 
washed  and  dried. 


SEPIA  TONES  BY  SULPHIDING. 

We  will  begin  with  the  sepia  tone,  since  it  is  the  most  popular  and 
pleasing  of  all  tones.  The  majority  of  the  methods  employed  at  the 
present  day  for  sepia  toning  are  based  upon  the  conversion  of  the  silver 
image  into  that  of  silver  sulphide.  The  silver  image  is  first  converted 
into  some  insoluble  salt  upon  which  the  sulphide  solution  can  act.  Any 
of  the  bleaching  solutions  already  given  will  answer  the  purpose.  The 
sulphide  solution  commonly  used  is  sodium  sulphide,  although  barium 
and  ammonium  sulphide  will  answer.  These  solutions  are  more  or  less 
unstable  and  costly.  The  formulas  about  to  be  described  are  inex- 
pensive and  the  “keeping  qualities’’  are  excellent. 

88 


There  are  a great  number  of  receipes  for  sepia  toning,  but,  how- 
ever, that  process  in  which  the  print  is  bleached  and  afterwards  toned 
is  by  far  the  best. 

The  bleached  and  well  washed  print  is  steeped  in: 


Sodium  sulphide  4 ounces 

Water 20  ounces 


This  solution  should  be  made  up  before  it  is  used.  This  stock 
solution  should  be  diluted  by  taking  of  it  3 ounces  with  sufficient  water 
to  make  20  ounces. 

In  the  course  of  a few  minutes  the  prints  change  from  a buff  or 
very  light  brown  to  the  desired  sepia  tone.  The  prints  are  then  rinsed 
in  water  for  a few  minutes  and  dried. 

SEPIA  TONE  WITH  HYPO-ALUM. 

Another  popular  process  for  sepia  toning  is  the  so-called  hypo-alum 
solution.  This  consists  of: 

Hypo 1 J/2  pounds 

Alum  3 ounces 

Water  (hot)  40  ounces 

Bring  the  solution  to  a boil  and  permit  it  to  simmer  for  1 0 to 
1 5 minutes.  To  this  solution  is  added  20  grains  silver  nitrate. 

The  toning  process  is  carried  on  at  about  1 20  deg.  F.  The  best 
results  or  tones  are  had  with  those  prints  which  were  previously  developed 
with  Amidol. 

SEPIA  TONES  WITH  SCHLIPPE’S  SALT. 

The  print  is  first  bleached  and  well  washed  in  running  water  for 
a short  while,  this  is  then  transferred  to: 

Schlippe’s  salt  1 ounce 

Water 20  ounces 

This  latter  solution  causes  the  print  to  turn  to  a yellowish  red  color, 
when  it  is  placed  directly  into  a 5 per  cent,  solution  of  ammonia  to 
soak  for  a few  moments.  Again  washing  in  running  water,  it  is  placed 


in  the  final  toning  solution  consisting  of: 

Copper  chloride  (10  per  cet.  solution)  1 ounce 

Hydrochloric  acid  ( 1 0 per  cent,  solution)  ....  1 ounce 

Water 20  ounces 


89 


, . A half  hour  immersion  in  this  solution  results  in  a handsome 
sepia  or  rich  brown  tone,  when  it  is  finally  washed  and  dried. 

The  advantage  of  this  process  is  that  the  objectional  odor  dfc  the 
sulphide  solution  is  absent. 

SEPIA  TONE  WITH  ARSENIC  ACID. 

Dr.  Kropf  (Photo.  Rund.  vol.  6,  page  97,  1913)  has  discovered 
that  arsenic  acid  would  produce  a rich  sepia  brown  tone  in  about 
20  minutes.  The  solution  he  recommends  coiwists  of: 

Potassium  bichromate 1 ounce 

Citric  acid  ( 1 0 per  cent,  solution)  . . 1 ounce 

Arsenic  acid  ( 1 0 per  cent,  solution)  . . I ounce 
Water 12  ounces 

The  silver  image  k con^ierted  into  that  of  silver  arsenide.  The 
function  of  the  potassium  bichromate  is  to  hasten  the  action  of  the 
arsenic  acid,  which  it  does  presumably  by  first  forming  silver  chromate 
which  is  more  readily  susceptible  to  the  arsenic  acid  than  the  silver  itself. 

Great  care  must  be  taken  in  handling  this  solution  as  it  is  extremely 
poisonous. 

SEPIA  TONES  WITH  SELENIUM. 

Namias  bleaches  the  print  and  afterwards  washes  thoroughly  and 
transfers  the  print  to  the  following  solution  for  a: 

Purple  Brown  Tone 


Water 20  ounces 

Sodium  sulphide  30  ounces 

Selenium 3 grams 


The  solution  must  first  be  filtered  before  being  used. 

BROWN  TONE  WITH  STANNOUS  CHLORIDE. 

The  bleached  image  is  washed  in  water  once  or  twice  and  a selu- 
tlon  of  sodium  stannite  then  poured  over  it.  The  image  appears  rapidly. 
The  stannite  solution  consists  of: 

Stannous  chloride 155  grains 

Water 3J/2  ounces 

To  which  is  added  18  c.  c.  of  a 40  dig.  Be;  sodium  hydroxide 
solution  and  sufficient  water  to  make  in  all  8^  ounces. 

Besides  intensifying  the  image  a brown  tone  is  obtained. 


90 


BROWN  TONES  WITH  URANIUM  NITRATE. 


With  potassium  ferricyanide,  uranium  nitrate  yields  a brown  solu- 
tion, containing  uranyl  ferrocyanide  and  potassium  nitrate,  thus: 

K6Fe2Cni2+UO  (N03)  (UO’^)  3Fe2Cn^2_^6KN03. 


A typical  solution  being: 

Uranium  nitrate  40  grains 

Potassium  ferricyanide  40  grains 

Acetic  acid 27  minims 

W ater 10  ounces 


The  negative  is  bleached,  intensified  and  toned  in  the  above 
solution.  This  is  due  to  the  silver  image  becoming  converted  into  silver 
ferrocyanide,  uranyl  ferrocyanide  being  simultaneously  formed.  Thus: 
2 (U02)  3Fe2Cn^2+2Ag2=Ag^FeCn6+3  (UO'3)  2FeCn6. 

Uranium  nitrate  is  but  little  used,  as  it  gives  the  negative  (when 
bleached)  and  the  print  a yellowish  color,  intensification  is  very  rapid 
and  bright  reddish  tones  are  obtained. 

The  simplest  way  to  dispose  of  the  coloration  is  to  steep  the  negative 
or  print  in  a 5 per  cent,  solution  of  ammonium  sulphocyanide  for  a few 
minutes  previously  to  the  final  washing. 

Since  the  brown  uranyl  ferrocyanide  is  not  completely  insoluble 
in  water,  negatives  so  intensified  must  not  be  washed  for  too  long  a 
time,  otherwise  the  uranyl  ferrocyanide  will  be  washed  away  and  the 
intensification  will  consequently  disappear. 


RED  TONES  WITH  COPPER  SULPHATE. 

The  well  washed  print  is  placed  in: 


Ammonium  carbonate  100  grains 

Potassium  ferricyanide  20  grains 

Copper  sulphate  10  grains 

Water 2 ounces 


A clear  dark  solution  results;  this  gives  a red  chalk  tone  in  about 
3 minutes.  The  toning  is  carried  on  until  the  deepest  shadow  is  con- 
verted, after  which  the  print  is  again  washed  for  about  1 0 minutes. 

Here  is  another  toning  solution.  This  one  gives  dark  red  prints. 
It  consists  of: 


91 


Potassium  ferricyanide 

. . . 2-3 

ounce 

Potassium  permanganate  . . . 

. . . 51/2 

grains 

Ammonia  (sp.  gr.  .91) 

K2 

ounce 

Copper  sulphate  

. . . 1 

ounce 

Sodium  citrate 

• ■ . 2/2 

ounces 

Water 

. . . 1 

gill 

To  remove  the  pinkish  tints  in  the  high  lights  place  the  print  in: 

Ammonia  (strong)  30  drops 

Water 6 ounces 

The  print  is  again  washed  in  water  and  dried.  '' 

RED  TONES  WITH  COPPER  CHLORIDE. 

Dr.  Namias  finds  that  the  tone  can  be  greatly  improved  by  using 


the  following  solution: 

Copper  sulphate 1 ounce 

Sodium  chloride 90  grains 

Hydrochloric  acid 50  minims 

Water 20  ounces 


In  this  solution  the  silver  ferrocyanide  is  converted  into  silver 
chloride  and  copper  ferrocyanide  is  formed,  which  increases  the  red 
color  of  the  print.  This  is  attained  in  a few  minutes,  about  five  at  the 
most. 

The  prints  must  be  well  rinsed  in  water  and  then  dipped  into  a 
1 0 per  cent  solution  of  hypo  containing  5 per  cent  of  boric  acid.  In 
this  the  silver  chloride  dissolves.  The  prints  obtained  by  this  process 
are  much  more  brilliant  in  red  than  those  obtained  with  the  ordinary 
copper  solutions. 


CRIMSON  TONES  WITH  GOLD  CHLORIDE. 

By  placing  the  sulphide  sepia  toned  print  in  a gold  chloride  solu- 
tion, beautiful  crimson  tone  is  obtained: 


Gold  chloride  2 grains 

Ammonium  sulphocyanide  20  grains 

Water  20  ounces 


92 


The  toning  process  is  gradually  built  up  from  that  of  a red  hue 
to  that  of  crimson,  taking  in  all  but  5 to  1 0 minutes.  When  the  desired 
tone  is  reached  the  print  is  washed  for  a few  minutes  and  then  transferred 
for  a minute  or  two  in  a hypo  solution  consisting  of: 

Hypo 3 ounces 

Water  20  ounces 

After  which  the  print  is  again  washed  in  running  water  and 
allowed  to  dry. 


LIGHT  BLUE  TONE. 

Example  /. 

A single  blue  toning  solution  consists  of: 


Ferric  ammonia  citrate 100  grains 

Potassium  ferricyanide  100  grains 

Acetic  acid  20  c.  c. 

Water  . 8 ounces 


LIGHT  BLUE  GREEN  TONE. 
Example  11. 


Ferric  chloride 3|/2  grains 

Ferric  oxalate 6|/2  grains 

Oxalic  acid 6*/2  grains 

Potassium  ferricyanide 3 grains 

Water  8 ounces 


These  solutions  have  a tendancy  to  intensify  the  print,  for  this 
reason  it  should  be  toned  with  care. 

BLUE  GREEN  TONE. 

Example  111. 

The  well  bleached  print  is  washed  and  placed  in: 


Cobalt  chloride  10  grains 

Hydrochloric  acid  30  c.  c. 

Water 10  ounces 


This  solution  will  keep  well  for  a long  time  in  amber  colored 
bottles. 


93 


GREEN  TONE. 

Example  I. 

The  following  solution  is  found  to  give  nice  warm  green  tones: 


Ferric  chloride 10  grains 

Oxalic  acid  (saturated  solution)  . . \]/^  ounces 

Vanadium  chloride  20  grains 

Nitric  acid  50  minims 

Water  to 5 ounces 

This  solution  keeps  fairly  well. 


GREEN  TONE. 

Fox  and  Hickey  are  granted  United  States  patent  1166123  for 


the  following  green  toning  solution: 

Vanadium  chloride 20  grains 

Ferric  ammonium  oxalate 10  grains 

Ferric  chloride  10  mmims 

Potassium  ferricyanide 20  grains 

Acetic  acid  (glacial)  10  minims 

Oxalic  acid 100  grains 

Water  to 20  ounces 


After  the  toning  is  complete  the  washing  is  done  in  running  water 
and  the  print  is  allowed  to  dry. 

By  bleaching  the  print  and  placing  it  in  any  of  the  following  solu- 
tions the  respective  tones  indicated  are  obtained: 


Orange  Tone. 

Mercury  chloride  3 grains 

Potassium  iodide  AYl  grains 

Water 10  ounces 

Yellow  Tone. 

Potassium  chromate  (neutral)  ....  4 grains 

Water 10  ounces 


94 


Green  T^one. 

Immerse  the  yellow  toned  print  in: 

Iron  perchloride 1 grain 

Water  1,0  ounces 

The  toned  print  is  then  washed  in  running  water  and  dried. 

TONING  WITH  ORGANIC  DEVELOPERS. 

On  page  26  is  described  a series  of  compounds  that  develop  and 
tone  the  image  simultaneously.  The  following  formulas  are  recom- 
mended by  Dr.  Fischer,  the  inventor,  as  giving  good  results: 


Greenish  Blue  Tone. 

Trichlor  alpha  naphthol 2 grams 

dissolved  in 

Acetone 20  c.c. 

being  added  to 

Para  phenylenediamine  hydrochloride . 2 grams 

Sodium  hydroxide  30  grams 

Water 20  ounces 

Blue  Tone. 

Alpha  naphthol 2 grams 

dissolved  in 

Acetone 20  c.c. 

being  added  to 

Dimethyl  para  phenylenediamine 

hydrochloride 2 grams 

Sodium  hydroxide  2 grams 

Water 20  ounces 

Red  Tone. 

Thio  indoxyl  carboxylic  acid 2 grams 

dissolved  in 

Acetone 40  c.c. 

being  added  to 

Mono  ethyl  para  phenylenediamine 

hydrochloride  ....  2 grams 

Potassium  hydroxide  40  grams 

Water  20  ounces 


95 


Yellow  Tone. 


Alpha  chlor  ethyl  aceto  acetate 2 grams 

dissolved  in 

Acetone  20  c.c. 

Diethyl  para  phenylenediamine 2 grams 

Potassium  hydroxide  40  grams 

Water  20  ounces 


Homolka  (Photo.  Korr.,  page  471,  1914)  points  out  that  with 
monomethyl  naphthoquinone  ether  a deep  blue  image  can  thus  be  ob- 


tained. The  working  formula  is: 

Monoethyl  naphthoquinone  ether  ....  10  grams 

Potassium  bromide 10  grams 

Sodium  hydroxide  grams 

Sodium  sulphite 50  grams 

Water 20  ounces 


The  image  appears  in  a few  seconds  and  development  is  complete  \ 

in  about  three  minutes.  On  fixing  the  color  is  brought  out.  I 

DYE  TONING.  | 

*■ 

There  is  still  another  process  of  toning.  This  consists  of  mordant-  i 

ing  dyes  onto  a bleached  image.  The  advantage  of  this  process  is  that  I 

the  colors  are  more  transparent  and  they  do  not  Intensify  the  print;  > 

furthermore  a greater  range  of  colors  may  be  had  for  use.  It  is  used 

practically  in  toning  motion  picture  films  and  in  certain  color  photo- 
graphic processes. 

Of  the  basic  dyes  the  following  is  found  to  give  the  best  results. 

Red  Dyes. 

Fuchsine  (Magenta),  Quinoline  red,  Rhodamine  B,  Phenosofra- 
nine.  Xylene  red.  Acridine  red  B,  Acridine  Orange.  > 

i 

Yellow  Dyes.  ^ 

Auramine,  Chrysoidine,  Safranine,  Bismarck  Brown.  ^ 

Green  Dyes. 

Methylene,  Brilliant,  Malachite,  Janus,  Iodine,  Emerald,  Dia-  ^ 

mond,  Victoria  and  Guinea  green. 


96 


Blue  Dyes. 

Methylene  blue,  Aniline  blue,  Victoria  blue,  Thionin  blue,  Tolui- 
dine  blue,  Turkey  blue.  Gentian  violet.  Methyl  violet.  Crystal  violet. 

Various  intermediate  tones  can  be  obtained  by  mixing  any  of  the 
above  dyes  in  its  proper  proportions. 

Namias.  Brit.  Jour,  of  Photo.,  page  69,  1909. 

The  print  is  bleached  in  a lead  ferrocyanide  solution,  this  is  con- 
verted into  a lead  sulphate  by  placing  the  print  in  the  following  solution: 


Sodium  sulphate 1 ounce 

Sulphuric  acid  (by  weight)  45  grains 

Water 20  ounces 


Onto  this  is  mordanted  any  of  the  dyes  already  given.  The  dye 
is  preferably  mordanted  by  means  of  a one  per  cent,  solution  of  copper 
sulphate  and  then  washed  in  a concentrated  hypo  solution  containing  7 
per  cent,  boric  acid. 

In  place  of  the  lead  sulphate  the  ferrocyanide  image  is  placed  in 
a one  per  cent,  solution  of  potassium  hydroxide.  After  washing  the 
dye  can  be  fixed  on  this  image.  Since  lead  hydroxide  is  less  opaque 
than  the  sulphate,  there  is,  as  a general  rule,  no  need  to  remove  it  from 
the  image. 

Tauleigne  and  Mazo.  United  States  patent  1059917,  April 
12,  1913. 

The  well  washed  print  is  placed  in  a solution  of  copper  chloride. 
The  silver  image  is  seen  to  change  to  a white  color,  being  transformed 
to  a double  silver  chloride  and  copper.  It  is  then  washed  in  running 
water  and  then  placed  into  a one  or  two  per  cent,  solution  of  potassium 
iodide,  the  image  assumes  a greenish  white  color.  The  print  is  placed 
in  any  of  the  dye  solutions  enumerated,  after  which  it  is  washed  in  water 
made  acid  with  acetic  acid.  The  print  is  fixed  in  a 20  per  cent,  solution 
of  potassium  iodide,  or  in  a 3 to  10  per  cent,  solution  of  tannin  and 
afterwards  washed  in  a solution  of  hypo  and  fixed  in  a 1 0 per  cent, 
solution  of  potassium  cyanide.  This  is  again  washed  in  an  acidulated 
(acetic  acid)  solution  and  then  in  running  water. 


97 


Traube.  United  States  patent  1 093503,  April  14,  1914. 


The  print  is  converted  into  silver  iodide  by  placing  it  in  the  bleach- 
ing solution  described  under  Example  VI  and  then  transferred  to  a dye 
solution,  after  it  is  fixed  in  the  ordinary  hypo  solution. 

Miller.  United  States  patent  12‘14940  Feb.  6,  1917. 

The  well  washed  print  is  bleached  in  the  solution  given  under 
Example  VI  and  cleared  in  sodium  bisulphite;  the  toning  is  done  in  an 
acid  dye  solution  until  the  desired  tone  is  obtained,  washed  and  dried. 

Crabtree.  United  States  patent  1279276,  Sept.  17,  1918. 

The  method  of  procedure  was  to  first  tone  the  image  in  the  copper 
toning  solution,  wash  and  dyed  until  the  desired  tone  is  obtained.  The 
copper  toning  solution  consists  of: 


Copper  sulphate 16  grams 

Ammonium  citrate  (neutral)  ....  50  grams 

Potassium  ferricyanide 16  grams 

Ammonium  carbonate 8 grams 

Water  to  1 gallon 


The  toning  should  be  carried  on  for  about  5 to  1 5 minutes  at  70 
deg.  F. 

It  is  important  to  keep  the  bath  covered  when  not  in  use  so  as  to 
exclude  the  light,  since  the  solution  is  light  sensitive. 

After  washing,  it  is  immersed  in  the  dye  solution,  a specific  formula 


advocated  is: 

I 

Fuchsine  4 grams 

Acetic  acid  (gliwiial)  20  c.c. 

Water  to 1 gallon 


Of  course  any  dye  may  be  used  in  the  place  of  the  one  given.  The 
dyeing  is  carried  on  for  5 to  1 5 minutes ; wash  until  the  high  lights  are 
clear. 

> 


98 


Compound  Tones. 

By  first  partially  toning  the  print  in  a copper  solution  so  that  the 
half  tones  are  completely  toned  but  the  shadows  only  partially,  washing 
for  10  minutes  and  then  completing  the  toning  process  in  a blue  toning 
solution,  the  residual  silver  in  the  shadows  is  toned  blue.  In  this  way  a 
double  tone  is  obtained,  the  shadows  appearing  dark  blue  and  the  half 
tones  reddish  brown. 

By  immersing  the  toned  print  in  any  of  the  dye  solutions  and 
washed,  the  dye  will  mordant  itself  to  the  half  tones  producing  a striking 
double  tone  effect. 

A suitable  blue  toning  solution  suggested  is: 


Potassium  bichromate 0.1  gram 

Ferric  ammonium  sulphate  5 grams 

Oxalic  acid  12  grams 

Potassium  ferricyanlde  4 grams 

Ammonium  alum  20  grams 

Hydrochloric  acid  ( 1 0 per  cent)  . . 4 c.c. 

Water  to  1 gallon 


The  print  should  be  washed  after  the  toning  process  is  completed. 
Ives.  United  States  patent  1 278668,  Sept.  10,  1918. 

The  well  washed  print  is  placed  in  the  bleaching  solution  des- 
cribed as  Example  IV  and  transferred  immediately  to  running  water 
and  allowed  to  remain  therein  for  about  a half  hour  or  more  to  free  the 
print  from  the  excess  chromic  acid,  but  discharges  rapidly  in  a weak 
solution  of  sodium  bicarbonate. 

The  print  is  then  dyed  in  any  of  the  dye  solutions  until  the  desired 
depth  has  been  obtained,  the  high  lights  are  cleared  by  placing  the  print 
in  a weak  acetic  or  hydrochloric  acid  solution.  The  print  is  then  washed 
in  running  water  and  allowed  to  dry. 


99 


CHAPTER  V. 


THE  DIAZOTYPE  PROCESS. 

There  are  several  printing  processes  based  on  the  peculiar  property 
possessed  by  certain  diazo  compounds  when  exposed  to  light  is  decom- 
posed and  by  development  will  produce  prints  in  a great  range  of  colors 
or  dyes.  These  colors  vary  with  the  particular  developer  used.  In 
Europe  several  large  concerns  manufacturing  table  cloths  and  tapestries 
are  using  these  processes  for  the  designs  found  as  borders.  It  is  not  used 
in  photography  as  the  process  is  somewhat  difficult  and  the  high  lights 
are  not  altogether  clear.  But,  however,  it  is  interesting  enough  to  ex- 
periment with,  in  the  possibility  that  someone  may  find  a simplified 
process. 

Green,  Cross  and  Bevan.  Jour.  Soc.  Chem.  Ind.  page  1001, 
1890. 

A sheet  of  paper  (or  other  surface  as  cloth,  etc.)  is  impregnated 
with  a diazo  compound  of  Primuline  and  on  exposure  to  the  sun  through 
a negative  the  following  colors  will  be  obtained  on  development  with: 


Beta  naphthol Red 

Beta  naphthol  disulphonic  acid Maroon 

Phenol  Y ellow 

Resorcinol  Orange 

Pyrogallol  Brown 

Para  phenylenediamine Brown 

Alpha  naphthylamine Purple 

Eikonogen  Blue 

The  sensitising  solution  consists  of: 

Primuline  320  grains 

Water  (hot)  20  ounces 

This  is  then  steeped  in  the  diazotising  solution: 

Sodium  nitrite  64  grains 

Hydrochloric  acid  150  minims 

Water  to  20  ounces 


100 


Transparencies  and  opals  can  be  made  by  coating  the  cleaned 
surface  with: 

Primuline  80  grains 

Gelatine 480  grains 

Alum  . . 2 grains 

Water 50  ounces 

This  process  should  be  carried  out  in  the  dark  and  allowed  to  dry 
in  a place  free  from  dust.  After  it  is  thoroughly  dried  it  is  exposed  to 
the  light  under  a negative  until  the  bare  glass  is  colorless.  Then  wash 
thoroughly  and  develop  in: 

For  Red  Tone. 


Beta  naphthol  

9/2 

grains 

Sodium  hydroxide 

128 

grains 

Water  to 

.20 

ounces 

For  Purple  Tones. 

Alpha  napththylamine  

190 

grains 

I hydrochloric  acid  

1 

ounce 

Water  to 

20 

ounces 

For  Blue  Tones. 

Eikonogen  

. 125 

grains 

Water  to 

. 20 

ounces 

For  Brown  Tones. 

Pyrogallol  

. 113 

grains 

Water  to 

. 20 

ounces 

Wash  well  after  development  and  dry.  The  high  lights  will  be 
found  to  be  blocked ; there  is  no  method  of  clearing  this  as  yet. 

Peer,  in  a communication  to  the  Mulhouse  Soc.  describes  the  use 
of  the  following  diazo  sulphites  to  give  the  colors  indicated: 


Aniline Orange 

Toludine e Orange 

Xylidine:  Red 

Cumidine  Red 

Benzidine  Violet 

Tolidine  Violet 

Dianisidine  Blue 

Here  are  typical  solutions  used : 

101 


Peer,  in  a communication  to  the  Mulhouse  Soc.  describes  the  use 
of  the  following  diazo  sulphites  to  give  the  colors  indicatad: 


Aniline Orange 

Toludine Orange 

Xylidine Red 

Cumidine Red 

Benzidine Violet 

Tolidine Violet 

Dianisidine Blue 

Here  are  typical  solutions  used: 

( 1 ) Sodium  toluol  diazosulphite 240  grains 

Beta  naphthol  240  grains 

Sodium  hydroxide  76  grains 

Water  to 20  ounces 

(2)  Sodium  ditolyl  tetrazosulphite 240  grains 

Para  phenylenediamine 190  grains 

Water 20  ounces 

(3)  Sodium  ditolyl  tetrazosulphite 240  grains 

Resorcinol  211  grains 

Sodium  hydroxide  154  grains 

Water 20  ounces 


On  the  exposed  parts  an  insoluble  dye  is  formed,  whilst  on  the 
unexposed  parts  the  compounds  remain  colorless  and  is  soluble  in  water. 
The  print  is  fixed  in  a solution  of  hydrochloric  acid. 

Andresen  discovered  in  1 894  another  diazo  printing  process,  the 
sensitiser  is  the  diazo  compound  of  alpha  naphthylamine  or  Beta  naph- 
thylamine,  the  former  giving  brownish  grey  images  and  the  latter 
brownish  red.  If  the  print  is  treated  with  tetra  azodiphenyl  ether,  violet 
images  are  obtained. 

Here  is  typical  solution  Andresen  used: 

Alpha  naphthylamine 220  grains 

Hydrochloric  acid  (sp.  gr.  1.1 9)..  152  grains 
Water  (boiling)  5 ounces 


102 


This  is  stirred  and  allowed  to  cool,  an  evolution  of  gas  will  take 
place  clhd  a yellowish  solution  is  formed  which  mu3b  be  filtered  into  an 
ice  cold  dish.  Apply  this  to  the  surface  and  dry  in  the  dark.  Expose 
for  2 to  3 minutes  under  a negative  in  the  sun  and  develop  in  a 1 0 to 
20  per  cent  solution  of  fused  sodium  acetate  and  wash  well  and  dry. 

Another  process  suggested  by  Andresen  consists  in  the  use  of 
diazotised  benzidine  sulphate,  which  is  made  as  follows: 

Pyridine  (base)  110  grains 

Water  (boiling)  10  ounces 

Then  add 

Sulphuric  acid 180  minims 

Water 180  minims 

Benzidine  sulphate  is  formed  and  partially  separates  out.  Cool 
this  solution  to  about  1 1 0 deg.  F and  add ; 


Sodium  nitrite  66  grains 

. Wafer  1 ounce 


in  small  quantities  with  continuous  stirring.  The  benzidine  sulphtete  is 
dissolved  and  diazotised  and  dissolves.  Filter  the  solution  and  pour  into 
five  times  its  volume  of  alcohol,  which  precipitates  the  diazo  compound, 
filter  out  the  precipitate  and  dissolve  (without  drying,  as  it  explodes 
when  dry)  in: 

Water  to 20  ounces 

The  paper  is  sensitised  in  this  cold  solution  for  two  minutes,  dried 
in  the  dark  and  exposed  under  a positive  or  transparency  and  then 
developed  in  a 2 per  cent  solution  of  amido  naphthol  sulphbnic  acid 
containing  2 per  cent  of  sodium  hydroxide.  Deep  blue  images  with 
pure  whites  are  obtained. 

Lumiere  and  Seyewetz,  in  1895,  took  up  the  study  of  the  com- 
binations indicated  by  Feer  in  order  to  obtain  simple  mono  chromes  in 
blue,  red  and  yellow  so  that  they  could  be  used  in  a three  color  process. 
The  following  are  the  solutions  employed  for  the  three  primary  colol-s: 

103 


YELLOW 


Diazo  ortho  toluidine  sodium  sulphite  2 grams 


Meta  amidophenol  1 gram 

Water 100  grams 


The  plate  is  steeped  in  this  solution  and  dried. 


RED 

(A)  Tetra  azotolyl  sodium  sulphite.  . . 1 gram 

Water 125  grams 

(B)  Beta  naphthylamine 

ether  hydrochloride . . .125  grams 

Water 125  grams 


The  plate  is  steeped  first  in  “A”  and  then  in  “B”  and  dried. 

BLUE 

(A)  Tetra  azoethyl  oxybenzidine  sulphate 1 gram 

Water 125  grams 

(B)  Alpha  naphthylamine  ether  hydrochloride.  . 2Yl  grams 

Water 125  grams 

The  material  is  steeped  first  in  “A”  then  in  “B”  and  dried.  It  is 
difficult  to  obtain  a pure  blue,  but  the  mixture  above  gives  a blue  very 
slightly  violet  in  shade. 

Schoen  in  1 900,  patented  a process  based  on  the  property  of 
amido  salicylic  acid  and  its  derivitives  to  furnish  diazo  compounds 
transformed  by  the  sunlight  into  red  colors.  Ortho  amido  salicylic  acid 
is  dissolved  in  dilute  hydrochloric  acid  and  this  solution  is  treated  w^ith 
its  molecular  equivalent  of  sodium  nitrite.  The  diazotation  product 
precipitates  and  is  filtered  off  and  washed.  It  is  a yellow  substance, 
soluble  in  water  and  alcohol  and  very  soluble  in  alkalies.  It  turns 
rapidly  to  red  under  the  action  of  the  sunlight.  The  material  to  be 
coated  is  steeped  in  a solution  of  this  product  in  dilute  ammonium  oi 
sodium  hydroxide  precisely  neutralized.  The  material  is  then  dried  at 
the  ordinary  temperature  in  the  dark  and  it  is  exposed  under  a negative 
until  the  print  shows  red.  It  is  fixed  by  sijnply  washing  in  water  or  some 
other  solvent  until  the  yellow  tint  of  the  untransformed  product  is  com- 
pletely dissolved  and  disappears.  The  red  print  is  fast  to  the  sun  light. 


104 


The  product  of  the  diazotation  of  amido  salicylic  acid  in  the  state 
of  an  alkaline  salt  is  still  more  sensitive  to  the  sun  and  gives  brighter 
tints.  The  diazo  product  of  para  brom  amido  salicylic  acid  is  orange 
and  is  very  stable  in  the  dark.  Under  the  action  of  the  sun  it  gives  a 
bright  and  very  fast  orange,  which  is  fixed  by  simply  washing  in  cold; 
water  from  three  to  five  minutes.  The  diazo  para  nitro  ortho  amido 
salicylic  acid  is  yellow,  but  it  is  too  unchangeable  in  the  sunlight  to  be 
of  any  practical  value.  All  these  colored  products  take  different  tints 
if  they  are  treated  with  lime  water  or  solutions  of  cobalt  nitrate,  ferric 
chloride  or  lead  acetate. 

Gros,  in  1901,  took  out  a F rench  patent  for  a process  of  obtaining 
photographic  prints  by  means  of  a leuco  base  of  the  triphenylmethane 
color  is  regenerated  under  the  action  of  the  sunlight  and  their  sensitive- 
ness can  be  increased  by  divers  products,  notably  by  the  silver  salts.  As 
an  example,  the  plate  is  impregnated  with  a 5 per  cent  solution  of  a 
leuco  base  of  Fluorescein  in  ether.  By  exposure  under  a negative  this 
gives  a red  positive. 

Ruff  and  Stein  in  1901  find  that  the  diazo  derivitives  so  far  pro- 
posed lack  in  snap  and  that  the  high  lights  are  blocked.  The  processes 
are  also  difficult  to  prepare  and  work. 

They  recommend  in  place  of  the  unstable  diazo  carbazol  the  stable 
compound  which  it  forms  with  certain  metallic  salts,  principally  with 
zific  chloride.  If,  instead  of  using  a positive,  the  exposure  is  to  be  made 
under  a negative  the  plate  sensitised  with  3-carbazol  diazo  sodium  sul- 
phonate. 


In  1 906  La  Moniteur  Scientific  published  a patent  granted  to 
Meister,  Lucius  and  Bruning,  which  consists  of  mixing  a leuco  base 
with  compounds  containing  nitrogen  and  oxygen  groups  that  are  easily 


105 


eliminated  by  catalysers.  As  an  example  the  following  is  recommended : 


Leucaniline 10  grams 

Alcohol  20  grams 

Ether  20  grams 

Collodion  (4  per  cent.)  50  grams 


This  preparation  is  coated  over  the  surface  and  dried  in  the  dark. 
Expose  to  the  sun  under  a negative,  at  the  end  of  a few  minutes  ex- 
posure the  print  is  colored  red,  this  is  fixed  by  washing  in  chloroform  or 
carbon  tetrachloride.  The  sensitiveness  of  the  preparation  can  be  in- 
creased by  the  addition  of  platinlc  chloride  and  turpentine,  and,  accord- 
ing to  the  leuco  base  employed,  prints  of  various  colors  are  obtained. 
The  leuco  basic  salts  of  the  Malachite  green  series  give  green  and  blue 
tints  and  those  of  Flavaniline  and  Auramine  give  yellow  prints. 

Damlanovich  and  Guglialmeth  in  1 909,  had  the  idea  of  beating 
albumen  up  with  its  own  volume  of  water  and  filterering.  The  filtrate 
is  then  spread  over  the  surface  and  dried  slowly  at  the  ordinary  temp- 
erature, then  sensitised  in  a cold  solution  of  sodium  nitrite  in  hydrochloric 
acid  in  the  dark  for  several  hours.  The  strength  of  the  solution  is  2 
per  cent.  The  prints  thus  treated  are  washed  carefully  and  dried  slowly 
in  the  dark.  The  albumen  takes  an  intense  yellow  tint,  unstable  in  the 
sun  and  in  decomposing  takes  a pale  green  tint.  Under  the  action  of 
phenol  in  alkaline  solution,  or  a phenolic  amine  in  acid  solution,  this  is 
transformed  into  a coloring  matter  with  analogous  properties  to  those 
obtained  by  coupling  diazo  compounds  with  the  same  phenols  or  amines. 

Baudisch  in  1911,  noted  that  when  a fibrous  material  is  impreg- 
nated with  a solution  of  ammonium  alpha,  nitroso  naphthyl  hydroxyla- 
mine  and  steamed,  the  fibre  takes  a light  yellow  or  dark  brown  color. 
If  it  is  then  exposed  to  the  sun  light  this  is  turned  to  a fast  red.  The 
color  is  brighter  if  the  steaming  has  been  done  in  the  presence  of  formic 
aldehyde. 


106 


A process  using  Indigo  published  in  the  bulletin  of  the  Mulhouse 
Soc.  is  in  the  nature  of  a decoloration  process.  The  following  mixture 
is  spread  over  the  surface  of  the  plate: 


Indigo  salt 

7.5 

grains 

Sodium  bisulphite  

0.01 

grains 

Sodium  hydroxide  

1.0 

grains 

Gum  water  

300.0 

grains 

Water 

4.0 

grains 

The  fibre  is  then  dried  in  the  dark  and  exposed  under  a negative  for 
an  hour  at  the  least.  The  exxposed  parts  turn  yellow  to  begin  with, 
then  brown.  The  print  is  developed  with  sodium  hydroxide  of  1 5 
deg.  Be.  at  60  deg.  C. 


107 


CHAPTER  VI. 


DIRECT  POSITIVES. 

The  production  of  positives  instead  of  the  usual  negatives  is  of 
great  importance  to  those  practising  with  the  Autochrome  and  similar 
color  photographic  processes.  There  are  a number  of  methods  in  use 
for  converting  the  negative  into  that  of  a positive,  of  these  there  are  only 
two  that  give  satisfactory  results  and  are  given  herewith. 

Col.  Waterhouse  first  described  the  use  of  thiocarbamide  (CS 
(NH^)  as  having  given  satisfactory  results.  The  formula  he  made 


use  of  is: 

Lithium  carbonate  50  grains 

Sodium  sulphite 50  grains 

Eikonogen  50  grains 

Thiocarbamide  (saturated  solution)  3 drops 

Water  10  ounces 


The  negative  appears  as  usual  and  then  it  apparently  assumes  a 
fog  all  over  the  surface,  this  is  then  exposed  to  diffused  light  and  re- 
placed in  the  developer;  after  three  or  four  minutes  the  positive  image 
is  clearly  seen.  This  is  then  fixed  and  washed. 


108 


Recent  exxperiments  by  Perley  (Jour.  Phys.  Chem.  vol.  1 3,  page 
649,  1 909)  with  thiocarbamide  and  Hydroquinone  show  better  results. 
Herewith  is  the  formula  he  made  use  of: 


(A)  Water  20  ounces 

Sodium  sulphite  126  grains 

Hydroquinone  21  grains 

(B)  Water  20  ounces 

Sodium  carbonate  126  grains 


Add  20  c.  c.  of  a concentrated  thiocarbamide  solution  to  25  c.  c. 
of  solution  A and  25  c.  c.  of  solution  B. 

The  tetra  thiourea  ammonium  bromide  recommended  by  Col. 
Waterhouse,  but  apparently  not  tried  by  Perley  or  other  investigators, 
is  very  much  superior  to  the  plain  thiourea,  giving  clearer  and  better 
positives.  The  following  is  the  formula  used: 

(A)  Water  6%  ounces 

Sodium  sulphite 390  grains 

Hydroquinone  65  grains 

(B)  Water 6J4  ounces 

Sodium  carbonate  830  grains 

(C)  Water 34  ounces 

Tetra  thiourea  ammonium 

bromide 15.5  grains 

For  use  take  one  part  A,  one  part  B and  two  parts  C. 

With  the  exception  of  the  temperature,  the  development  is  the  same 
as  for  other  negatives.  The  temperature  is  absolutely  essential  to  the 
successful  working  of  the  process.  The  limits  are  59  to  64  deg.  F ; 
and  they  must  be  strictly  adhered  to. 

The  corresponding  chloride,  however,  appears  to  be  better  still 
and  works  without  a restrainer  (potassium  bromide) . The  iodide  is 
not  satisfactory.  , 


109 


Satisfactory  postitives  were  obtained  with  an  Adurol  developer 
containing  a rather  large  amount  of  alkali,  but  with  Amidol  the  results 
were  unsatisfactory.  The  effect  of  Metol  is  very  peculiar.  A small 
amount  of  it  added  to  the  regular  Hydroquinone  developer  increases 
very  much  the  density  of  the  negative  image.  Hybrides  generally  result, 
although  by  decreasing  the  exposure  very  much  and  developing  for  a 
short  time,  some  rather  poor  positives  would  be  obtained. 

All  these  compounds  were  prepared  according  to  the  directions  of 
Reynolds  (Jour.  Chem.  Soc.  vol.  59,  page  384,  1891), 

The  manufacturers  of  the  Autochrome  plates  advocate  the  follow- 


ing: 

Potassium  permanganate  18  grains 

Sodium  bisulphite 1 ounce 

Water  20  ounces 


The  method  of  precedure  is  the  same  as  with  thiocarbamide  salts. 


CHAPTER  VII. 


RECOVERY  OF  SILVER  FROM  HYPO. 

^The  largest  use  of  silver  at  the  present  day  is  in  photography.  It 
IS  natural  that  a considerable  amount  should  find  its  way  into  silver 
refining  and  sweeps  trade.  It  may  be  said,  however,  that  a smaller  per- 
centage is  obtained  from  photographers  than  should  be  produced  for 
the  reason  that  many  photographers  make  no  attempt  to  save  their  solu- 
tion, but  throw  them  away  regularly.  This  fact  is  quite  true  of  a large 
percentage  of  those  who  work  with  dry  plates  and  films,  and  especially 
those  who  do  developing  for  the  amateur  trade,  as  they  are  not  familiar 
with  the  method  of  saving  the  silver  or  disposing  of  it  after  saving  it. 
With  the  old  wet-plate  process,  photographers  were  compelled  to  save 
their  silver  wastes,  for  the  reason  that  it  amounted  to  a very  large  quan- 
tity and  was  of  a character  that  could  readily  be  reclaimed.  The  v/et- 
plate  process  is  now  used  only  to  a limited  extent  and  is  almost  confined 
to  the  photo-engravers’  trade;  practically  every  professional  photo- 
grapher now  employs  the  dry  plates  which  have,  as  every  one  knows, 
been  the  cause  of  the  present  popularity  and  enormous  growth  of  both 
professional  and  amateur  photography.  Had  it  not  been  for  the  advent 
of  dry  plates  the  art  of  photography  would  never  have  been  what  it  is 
today. 

The  methods  for  recovering  the  silver  from  photographers’  solu- 
tions herein  given  apply  only  to  dry-plate  work,  as  the  wet-plate  process 


is  used  so  rarely  that  it  is  unnecessary  to  consider  it  as  a factor  in  the 
matter  of  silver  saving  when  carried  out  according  to  the  method  here- 
with described. 

“Hypo”  Solutions  the  Only  Ones  Worth  Saving 

The  modern  photographer,  who  uses  dry  plates,  has  quite  a number 
of  solutions,  but  the  principal  ones  are  the  two  following: 

1 . The  developer.  , 

2.  The  fixing  solutions. 

The  other  solutions  are  of  little  importance  as  they  are  seldom 
used  and  contain  no  silver.  These  solutions  are  generally  employed  ibr 
reduction  or  intensification  of  the  silver  image  on  the  plate  and  cannot 
be  considered. 

The  developer  is  the  solution  used  to  bring  up  the  image  on  the 
exposed  dry  plate  and  contains  no  silver  when  fresh  and  unused.  After 
using,  it  contains  traces  of  silver,  but  not  of  sufficient  quantity  to  warrant 
saving.  The  developer,  therefore,  is  of  no  value  and  should  not  be 
saved. 

After  the  developer  has  brought  out  the  image  on  the  dry  plate 
there  still  remains  the  bromide  of  silver  that  has  not  been  acted  upon  by 
the  light  during  the  exposure  of  the  plate  through  the  lens  in  ttie  camera. 
1 he  portions  of  the  plate  that  have  been  acted  upon  by  the  light  are 
reduced  by  the  developer  and  are  converted  into  metallic  silver,  which 
constitutes  the  image.  The  portions  unacted  upon  by  the  light  are  not 
reduced  by  the  developer  and  thus  remain  as  bromide  of  silver. 

When  the  developing  process  is  completed  the  dry  plate  must  be 
“fixed,”  and  this  consists  of  soaking  it  in  a solution  of  hyposulphite  of 
soda,  as  it  is  usually  called  “hypo.”  This  material  has  the  property 
of  dissolving  the  bromide  of  silver,  but  does  not  dissolve  the  black 
metallic  silver  formed  as  the  image  by  the  developer.  In  this  manner, 

112 


therefore,  all  the  silver  unacted  upon  by  the  light,  and  which  is  in  the 
form  of  bromide  of  silver  ig  dissolved  from  the  plate,  leaving  untouched 
the  black  reduced  silver  comprising  the  image.  (The  plate,  of  course, 
is  coated  with  gelatine  remains  on  the  surface  of  the  glass.)  A glass 
negative,  therefore,  that  has  been  developed  and  fixed,  as  well  as  washed 
and  dried,  contains  the  image  in  the  form  of  silver  imbedded  in  thej 
gelatine. 

The  “fixing  solution”  or  that  used  to  dissolve  the  unacted-upon 
bromide  of  silver  from  the  plate,  is  the  only  one  that  contains  sufficient 
silver  to  be  worth  saving.  This  fact  should  be  impressed  upon  photo- 
graphers, many  of  whom  save  all  solutions,  so  that  only  the  fixing  bath 
will  be  retained.  If  this  is  done  the  operations  are  somewhat  simplified. 


What  the  hypo  solution  is 

The  so-called  “hypo”  solution,  used  for  dissolving  the  bromide  of 
silver  on  the  dry  plate  that  has  been  unacted  upon  by  the  light,  consists 
of  a nearly  saturated  solution  of  hyposulphite  of  soda  (sodium  thiosul- 
phate) in  water.  It  is  frequently  used  alone,  but  more  often  contains 
alum.  The  alum  is  used  in  connection  with  it  to  harden  the  gelatin 
on  the  glass  and  prevent  it  frilling  at  the  edges.  The  use  of  alum  is 
now  extensive  and  nearly  all  photographers  employ  it.  In  addition  to 
the  alum  (either  ordinary  alum  or  chromic  alum  may  be  used)  small 
quantities  of  acetic  acid,  sulphuric  acid,  sulphate  of  soda,  oxalic  acid 
or  other  weak  acids  are  employed  to  render  the  solution  slightly  acid. 
The  principal  ingredient,  however,  is  the  hyposulphite  of  soda,  and  it  is 
this  substance  which  dissolves  the  bromide  of  silver. 

It  is  customary  for  photographers  to  use  their  hypo  solutions  until 
nearly  “exxhausted,”  so  to  speak,  or  until  they  work  slowly.  They 
are  then  discarded  and  new  ones  made  up. 


113 


Recovering  the  Silver  from  the  “Hypo"  Solution 

As  the  hypo  solution  is  the  only  one  used  by  photographers  which 
contains  sufficient  silver  to  pay  for  treatment,  it  is  upon  this,  therefore, 
that  we  must  concentrate  our  attenion.  The  removal  of  he  silver  is 
simple. 

The  first  thing  to  do  is  to  render  the  hypo  solution  slightly  alkaline 
by  the  addition  of  a little  carbonate  of  soda  solution.  Add  just  enough 
to  make  slightly  alkaline.  In  other  words,  red  litmus  paper  should 
turn  blue  when  wet  with  it. 

Now  add  a little  solution  of  liver  of  sulphur  in  water  to  this  hypo 
solution  and  allow  it  to  stand  in  a warm  place  for  a short  time.  The 
liver  of  sulphur  will  precipitate  immediately,  but  takes  a few  minutes 
to  form,  and  if  warmed  the  formation  takes  place  more  rapidly.  Its 
formation  can  be  seen  by  the  presence  of  black  flocks  of  sulphite  off 
silver,  which  settle  down  to  the  bottom  of  the  vessel.  When  the  top  of 
the  solution  is  clear,  add  some  more  of  liver  of  sulphur  solution  and  see 
if  a sufficient  quantity  has  been  adde'd  to  precipitate  all  the  silver.  If 
not,  add  more.  The  idea  is  to  avoid  adding  too  large  an  excess  of  the 
liver  of  sulphur,  although  a moderate  excess  is  not  harmful. 

When  enough  liver  of  sulphur  has  been  added  to  precipitate,  or 
“throw  down,”  all  of  the  silver  in  the  hypo  solution  the  whole  should  be 
allowed  to  stand  in  a warm  place  for  about  an  hour  to  give  it  an  oppor- 
tunity to  settle.  tA  the  end  of  this  time  the  black  sulphide  of  silver  will 
be  found  on  the  bottom  of  the  vessel.  The  clear  solution  at  the  top, 
should  be  tested  with  liver  of  sulphur  to  make  sure  there  is  no  silver  left, 
and  if  this  is  the  case  it  may  be  siphoned  off  and  thrown  away. 

The  sulphide  of  silver  on  the  bottom  should  be  washed  off  with 
water,  by  stirring  up  with  clear  water  and  then  allowed  to  settle.  The 
clear  liquid  is  again  siphoned  or  poured  off  and  the  washing  operation 
repeated.  This  may  be  carried  on  several  times,  and  the  whole  poured 


onto  a filter  paper  in  a large  glass  funnel  and  the  silver  sulphide  filtered 
out.  While  on  the  filter  it  should  be  washed  several  times  with  clear 
water. 

If  everything  has  been  done  well  there  is  obtained  a mass  of  fairly 
pure  sulphide  of  silver  in  the  moist  state.  This  should  be  dried.  Pure 
sulphide  of  silver  contains  87.09  per  cnt.  of  mtallic  silver. 

If  one  desires  to  reduce  this  to  metallic  silver,  the  best  way  is  to 
dissolve  it  in  diluted  nitric  acid,  filter  off  the  sulphur  that  separates,  and 
precipitate  the  metallic  silver  by  means  of  copper,  sheet  or  wire.  Such 
a procedure,  however,  is  not  advisable,  as  the  sulphide  of  silver  is  always 
salable  and  is  readily  purchased  by  silver  smelters  and  refiners.  They 
do  not,  however,  as  a rule,  like  to  purchase  the  hypo  solution,  for  the 
reason  that  it  usually  does  not  contain  sufficient  silver  in  the  manne^r 
described,  therefore,  the  silver  sulphide  obtained,  even  when  wet,  is  so 
rich  that  it  will  pay  transportation  to  a long  distance.  The  operation  of 
precipitating  is  so  simple  that  photographers  can  do  it  at  frequent  inter- 
vals and  gradually  accumulate  the  sulphide  of  silver,  so  that  when  it  has 
reached  a sufficient  amount  it  can  be  sold  to  silver  smelters.  Or,  if  it 
is  not  desired  to  sell  it,  the  silver  can  be  reduced  as  previously  mentioned. 
It  will,  it  is  believed,  be  found  preferable  to  sell  the  sulphide  of  silver, 
for  the  reason  that  there  is  no  use  for  either  metallic  silver  or  nitrate  of 
silver  in  the  photographic  studio  when  dry  plates  are  employed. 


115 


CHAPTER  VIII. 


PHOTOGRAPHIC  BRONZE  AND  PLASTER  PLAQUES. 

In  1861  M.  Willeme  was  successful  in  making  plaster  casts  in 
relief  from  photographic  negatives.  To  carry  out  this  process  a series 
of  cameras  was  required  as  well  as  various  devices  such  as  pantographs 
to  make  the  impression  in  the  plaster.  This  process  fell  into  oblivion, 
inasmuch  as  it  depended  too  much  on  the  skill  of  the  photograph-sculptor 
for  the  best  results. 

Other  attempts  were  made,  and  these  again  proved  a fialure. 
Eventually  the  well-known  swelling  property  of  so-called  “bichromated 
gelatine”  was  adopted. 

The  process  involved  is  quite  simple,  and  consists  of  eight  succes- 
sive steps  in  the  production  of  a photograph  in  bas-relief,  either  in  plaster- 
of-paris  or  in  copper.  These  are  as  follows: 

1 . Secure  a good  sharp  negative  (of  a head)  in  profile. 

2.  Make  a print  in  the  bichromated  gelatine. 

3.  Swell  (or  develop)  this  latter  plate. 

4.  Mordant  roharden  the  image. 

5.  Make  a plaster  negative  or  impression. 

6.  From  this  latter  secure  a duplicate  in  wax. 

7.  Coat  with  graphite. 

8.  Electroplate  with  copper. 


1 16 


making  the  gelatine  plate. 

Use  an  enameled  iron  pot  and  into  it  place  V/i  ounces  of  Nelson's 
soft  gelatine,  1 0 ounces  water  (distilled) , and  6 drops  glycerine. 

Allow  the  mass  to  stand  until  the  gelatine  swells  and  becomes  soft. 
Then  heat  the  pot  (preferably  in  a water  bath)  until  the  mass  dissolves, 
taking  care,  however,  that  the  temperature  does  not  exceed  120  deg. 

F.  When  the  mass  is  entirely  dissolved  add  1 50  grains  of  potassium 
bichromate  and  75  grains  of  ammonium  bichromate,  stirring  thoroughly 
and  keeping  the  solution  at  1 20  deg.  F.  Then  filter  it  through  muslin 
into  a glass  graduate  that  has  been  heated  to  1 30  deg.  F.  All  this 
must  be  done  in  a dark  room,  using  only  a ruby  lamp  for  light. 

In  the  meantime  a piece  of  glass  about  5 by  7 inches  in  sizQ  and 
inch  thick  is  ca’refeully  cleaned  and  warmed;  this  plate  is  coated 
with  the  gelatine  solution.  Great  caie  must  be  taken  that  the  coating 
is  not  put  on  in  streaks  and  does  not  run  over  the  edges.  The  gelatine- 
coated  plate  is  then  placed  in  a dark  room  or  box  and  allowed  to  dry. 
The  temperature  of  the  room  must  be  about  95  deg.  F.  The  best  results 
are  obtained  with  plates  coated  at  the  rate  of  three  ounces  to  each  plate. 
Leave  the  plates  to  age  for  three  days. 

Secure  a good,  sharp  photographic  negative,  preferably  one  of  a 
head  in  profile,  and  expose  the  gelatine-coated  plate  through  this  for 
about  fifteen  minutes  to  direct  sunlight  or  for  one  hour  to  ordinary  dif- 
fused daylight. 

After  exposure  remove  the  plate  from  the  printing-frame,  and 
place  it  face  up  in  a dish  of  clean,  cool  water.  The  gelatine  will 
mediately  begin  to  swell.  The  parts  of  the  gelatine  film  that  have  not 
been  acted  upon  by  light  wall  absorb  water  and  swell  up.  The  other 
parts,  which  correspond  to  the  transparent  portion  of  the  negative  and 
which  have  been  acted  upon  by  light,  have  become  insoluble  and  will 
not  be  affected  by  the  water,  so  that  they  remain  at  their  original  level. 
The  progress  of  the  swelling  can  be  ascertained  both  visually  and  by 
feeling  with  the  tip  of  the  finger. 


Should  the  swelling  be  allowed  to  proceed  too  far,  the  edges  of  the 
lines  will  absorb  water,  and  in  the  finished  print  the  surface  will  be  con- 
vex. If  not  swelled  sufficiently  the  relief  will  be  shallow  and  the 
lines  slightly  concave.  When  it  is  judged  that  the  relief  is  sufficient, 
remove  the  plate  from  the  dish,  and,  after  washing  under  the  tap,  place 
it  in  another  dish  containing  a hardening  solution  made  up  of  36  ounces 
water,  ]/2  ounce  chrome  alum,  and  ounce  citric  acid.  After  remain- 
ing in  htis  solution  from  three  to  five  minutes,  remove  the  plate  and  wash 
it  thoroughly. 

Lay  the  plate  on  a level  slab,  and  place  iron  bars  ^2  inch  in  thickness 
about  one  inch  from  the  edges  of  the  glass  and  parrellel  with  them.  The 
bars  should  be  well  greased  with  lard  or  oil  to  prevent  the  plaster  sub- 
sequently used  from  adhering  to  them. 


- THE  PLASTER  CAST. 

Now  prepare  the  plaster-of-Paris  (grade  XXX)  by  pouring  a lit- 
tle water  into  a basin  and  adding  the  plaster  until  it  is  the  consistency 
of  treacle.  To  this  add  a handful  of  powdered  alum.  It  is  best  to' 
pass  the  plaster  through  a fine  sieve  to  remove  any  large  or  rough  par- 
ticles of  foreign  matter.  The  mixture  should  be  well  worked  up  with  a 
wooden  spoon,  or  stirred,  and  this  should  be  done  rapidly,  or  the 
plaster  will  set  during  the  operation. 

As  soon  as  it  is  mixed,  carefully  pour  the  plaster  upon  the  swelled 
gelatine  print  until  the  space  between  the  bars  is  completely  filled  and  is 
rather  higher  than  the  bars,  care  being  taken  to  avoid  air  bubbles.  It 
should  be  pressed  down  with  a large  shallow  spoon  or  spatula.  When 
the  plaster  begins  to  set,  scrape  the  surface  level  with  a straight-edge 
resting  on  the  bars,  and  when  set  hard  insert  the  edge  of  a knife  beneath 
one  end  to  push  the  glass  and  cast  apart,  removing  the  irons  and  trim- 
ming the  edges.  It  is  a matter  of  experience  to  determine  how  long  to 
leave  the  plaster  before  lifting  it  from  the  gelatine  print.  By  pressing 

118 


the  finger  on  the  back  the  time  can  be  judged.  When  it  takes  some 
pressure  to  make  an  impression  the  cast  may  be  considered  ready  to  lift. 
Thus  is  produced  a negative  in  plaster,  from  which  a copy  is  to  be  made 
in  wax. 

Copying  in  wax  is  done  by  removing  the  moisture  from  the  face  of 
the  plaster  negative  with  the  aid  of  a cloth  or  sponge.  The  plaster 
negative  is  then  laid  flat  and  the  iron  bars  again  laid  in  the  same  position 
as  when  the  plaster-of-paris  was  molded.  Now  pour  upon  this  negative 
to  the  height  of  ^/i  inch  8 ounces  beeswax,  32  ounces  paraffin,  and  6 
ounces  rosin.  When  this  has  congealed  or  hardened  separate  it  with 
a knife.  Now  give  the  wax  print,  or  positive,  a surface  of  fine  graphite, 
and  place  it  in  a shallow  basin,  leaving  in  it  a concentrated  solution  of 
copper  sulphate.  Sprinkle  upon  the  surface  of  the  wax  image  some 
fine  iron  filings.  A fine  copper  film  will  immediately  form  on  the  surface 
of  the  graphite.  Wash  in  running  water  and  copper  plate  in  the  usual 
manner. 

It  must  not  be  supposed  that  this  process  is  to  become  a competitor 
of  the  sculptor,  but  it  is  really  intended  to  be  a valuable  aid  to  him.  It 
may  be  commercially  used  for  making  signs,  medals,  cameos,  brooches, 
and  architectural  pieces. 


119 


IMPORTATION  OF  DEVELOPERS. 


Norton.  Department  of  Commerce  report  on  importation  of  de- 
velopers and  dye  sensitizers  for  the  fiscal  year  1913-1914. 


Compound 

Pounds 

Value 

Para  nitrophenol 

4780 

$ 770 

Para  amidophenol 

10631 

1684 

hydrochloride  652 

189 

Para  phenylenediamine  . . . 

11088 

3414 

Metol 

10582 

13658 

Ortho  amidophenol  

625 

223 

Diamidophenol  

441 

391 

Pyrogallol 

23615 

20476 

Hydroquinone 

66596 

25140 

Pinacyanol  

40 

Pinachrome 

30 

120 


' NAME  AND  SUBJECT  INDEX 

PAGE 

Acetone 95,  96 

Acridine  orange 96 

red  B 96 

Adurol  59,  74,  no 

Alpha  chlor  ethyl  aceto  acetate 96 

naphthol 95 

trichlor 95 

Alum 77,  89 

Alpha  naphthylamine  1 00,  1 02 

ether  hydrochloride 104 

Amidol 60,  68,  71,  72,  74,  89,  110 

Amido  naphthol  sulphonic  acid 103 

salicylic  acid  104 

Ammonia 85,  92 

Ammonium  alum  99 

bichromate  117 

bromide  79 

carbonate 91,  98 

chloride  78 

citrate  * 98 

Molybdate 87 

Persulphate 81,  82 

sulphide  . 85 

sulphocyanide 80,  92 

Andresen ^ 92,  1 03 

Aniline ^91 

blue 97 


121 


PAGE 


Arsenic  acid 90 

Autochrome  110 

Auramine 96,  106 

Barium  sulphide 85 

Baudisch  106 

Beeswax  119 

Beta  naphthol  1 00,  1 02 

disulphonic  acid 100 

ether  hydrochloride  104 

naphthylamine  104 

Benzidine 101 

sulphate  103 

Bichromated  gelatine 116 

Bismarck  brown  96 

Bleaching 77 

with  the  ferricyanides 79 

and  intensification 76 

Boric  acid  92,  97 

Brewster 68 

Brilliant  green  96 

Brougham  80 

Bronze  plaqiKS 116 

Calcium  chromate  84 

Calomel  78 

Carnegie 83 

Ceric  sulphate ^ 84 

Chromic  acid 79,  99 

Chromium  81,  83,  84 

dioxide  83, 

Chrysoidine  96 

Cobalt  chloride  93 

Compound  tones  99 


122 


PAGE 


Copper lie 

bromide 

sulphate 

. .82. 

87,  91.  92,  97,  98 

Crabtree 

Cros  

Crystal  violet  

Cumidine 

Cupric  chloride  

Damianovich 

Deck  

Desalme 

Developers,  importation  of  

120 

Developing 

59 

Developers  alkaline  

factors  of  

Diamine 

61 

Diamond  green  

96 

Dianisidine 

101 

Diazo  carbazol  sodium  sulphonate 

105 

ortho  toluidine  sodium  sulphonate.  . . 

104 

Diazotype  process  

100 

Dichroic  veil  

76 

Dimethyl  para  phenylenediamine . 

95 

Diphenal  

61 

Direct  positives  

108 

Duratol  

61 

Dye  toning  

96 

Eastman  Kodak  Co 

70 

Edinol  

60,  74 

Eikonogen 

. .61, 

62,  74,  100,  108 

Emerald  green 

96 

Factor  of  combined  developers 

75 

123 


PAGE 


Factorial  development 7-3 

Factor  six  75 

Farmer’s  reducer  80,  81 

Feer 101,  103 

Ferric  ammonium  citrate 93 

oxalate 94 

sulphate 99 

chloride 93,  94,  95 

Ferrous  oxalate  86,  93 

Fischer 95 

Flavaniline 106 

Fluorecein 105 

Formaline 77 

Fuchsine  96,  98 

Gear  80 

Gelatine .......  . 117 

Gentian  violet 97 

Glycin  62,  63,  74 

Gold  chloride  92 

Graphite 119 

Green  dyes  96 

Guglialmeth  1 06 

Guinea  green  94 

Flardening  77 

Homolka  96 

Hunter 81 

Hydramine 63 

Hydroquinone . .63,  64,  69,  74,  75,  80,  84,  109,  110,  120 

Hypo 76,  78,  80,  82,  86,  89,  92,  93,  97,  98,  1 1 2,  114 

test  for 77 

recovery  of  silver  from Ill 

Importation  of  developers 120 


124 


Irdigo  salt  . . . 
IntensificalHon  . 
Iodine 


PAGE 


green  

Ives 

Janus  green  

Lead  nitrate 

sulphate 

Liesegang  

Leucaniline 

Lithium  carbonate  

Lumiere - 

Magenta 

Malachite 

Mazo 

Meister,  Lucius  and  Bruning 

Mercurous  chloride 

Mercury  chloride  

iodide 

Meta  amidophenol  

Methylene  blue  

green  

Methyl  glycin 

violet  

Metol 64, 

Metoqoinone 

Miller  

Mono  ethyl  naphthoquione  ether  . . . , 
ethyl  para  phenylenediamine . . 

Monomet 

Mulhouse  Soc 

Namias  


107 

77,  80 

80 

96 

99 

96 

82,  83 

97 

67 

106 

108 

64,  84,  103 

96 

96,  106 

97 

105 

78 

78,  79,  94 

78,  79 

104 

97 

96 

_ 63 

97 

65,  66,  74,  75,  80,  110,  120 

; 64,  74 

98 

96 

95 

65 

107 

81,  97 


125 


PAGE 

Naphthoquinone  ether,  monoethyl  96 

Norton  120 

Ortol 65,  74,  120 

Oxalic  acid ‘ 93,  94,  99 

Para  amidophenol 65,  66,  67,  74,  120 

Paraffin  119 

Para  phenylenediamine  68,  95,  100,  120 

dimethyl  95 

monoethyl 95 

Perley  109 

Phenol 100 

Phenosafranine 96 

Phenyl  hydrazine 67 

hydroxylamine 68 

Pinachrome  120 

Pinacyanol 120 

Piper 83 

Plaster 119 

cast  118 

Potassium  bichromate 83,  90,  94,  99,  1 17 

bromide  79 

cyanide  97 

ferricyanide 79,  80,  83,  91,  92,  93,  94,  98,  99 

iodide  78,  79,  80,  94,  97 

permanganate 77,  80,  81,  82,  92,  110 

sulphide  85 

Primuline 100 

Pyridine  103 

Pyrocatechin 69,  74 

Pyramidol  68 

Pyrogallol 60,  61,  65,  69,  70,  71,  120 

acetone 70 

soda  70,  100 

factor  of  74 

Quinoline  red 96 

Red  dyes  96 

Reducer,  Farmer’s  80 

Reducin 71 


126 


Resorcinol  

Reynolds  

Rhodamine  B 

Rodinal 

how  it  is  made 

Ruff  

Safranine  

Salicylic  acid,  amido  

Schlippe’s  salt  

Schoen  

Selenium 

sepia  tones  with  arsenic  acid 

selenium 

sulphiding 

hypo-alum. 

Schlippe’s  salt  .... 

Seyewetz  

Silver  iodide  

nitrate  

sulphide 

recovery  of,  from  hypo 

Sodium  chloride 

citrate 

ditolyl  diazosulphite  

tetrazosulphite  . ... 

nitrite  

phosphate  

stannite 

sulphate 

sulphide 

sulphite 

Stannous  chloride 

Stein  . 

Synthol  

Tauleigne  

Tetra  azoethyl  oxybenzidine  sulphate 
azotolyl  sodium  sulphite  .... 
thiourea  ammonium  boromide  . 

127 


PAGE 

100,  102 

100 

96 

61,  65,  67,  71,  72,  74 

71 

105 

96 

104 

87,  89 

104 

90 

90 

90 

88,  92 

89 

89 

103 

98 

86 

115 

Ill 

82,  92 

92 

102 

102 

100,  103 

79 

90 

97 

85,  89,  90 

79,  85 

90 

105 

72 

,97 

104 

104 

109 


PAGE 


Thiocarbamide 

Thioindoxyl  carboKylic  acid 

Thionin  blue  

Tolidine 

Toluidine 

blue 

Tone  compound 

crimson 

blue  . . . 

brown  . 

green  

maroon 

orange  

purple 

red 

sepia 

violet  

yellow 

Toning 

with  dyes 

Trichlor  alpha  naphthol  . . 

Traube 

Turkey  blue 

Uranium  nitrate 

Vanadium  chloride 

Valenta  

Victoria  blue 

green  

Von  Hubl 

Waterhouse 

Watkins 

Wax,  bees 

Yellow  dyes  

Xylene  red  

Xylidine 


76,  108,  109 

95 

97 

.• 101 

101 

97 

98 

92 

93,  95.  100,  101,  103,  104 

90.  91,  100,  101,  102 

94,  95 

100 

94.  100 

100,  101 

91,  92,  95,  100,  101,  102,  104 

88,  89.  90 

101 

94,  96,  100,  104 

88 

96 

95 

98 

97 

87,  91 

94 

63 

97 

96 

62 

'...108,  109 

73 

119 

96 

96 

101 


128 


^'3 


Sii 


